diff --git a/docs/cli-reference/index.md b/docs/cli-reference/index.md
index d481179dc..34f1d7b89 100644
--- a/docs/cli-reference/index.md
+++ b/docs/cli-reference/index.md
@@ -11,7 +11,7 @@ This documentation is auto-generated from test cases.
 | 📁 [Base Options](base-options.md) | 10 | Input/output configuration |
 | 🔧 [Typing Customization](typing-customization.md) | 29 | Type annotation and import behavior |
 | 🏷️ [Field Customization](field-customization.md) | 24 | Field naming and docstring behavior |
-| 🏗️ [Model Customization](model-customization.md) | 39 | Model generation behavior |
+| 🏗️ [Model Customization](model-customization.md) | 40 | Model generation behavior |
 | 🎨 [Template Customization](template-customization.md) | 21 | Output formatting and custom rendering |
 | 📘 [OpenAPI-only Options](openapi-only-options.md) | 7 | OpenAPI-specific features |
 | 📋 [GraphQL-only Options](graphql-only-options.md) | 1 |  |
@@ -194,6 +194,7 @@ This documentation is auto-generated from test cases.
 - [`--use-decimal-for-multiple-of`](typing-customization.md#use-decimal-for-multiple-of)
 - [`--use-default`](model-customization.md#use-default)
 - [`--use-default-factory-for-optional-nested-models`](model-customization.md#use-default-factory-for-optional-nested-models)
+- [`--use-default-keep-required-non-nullable`](model-customization.md#use-default-keep-required-non-nullable)
 - [`--use-default-kwarg`](model-customization.md#use-default-kwarg)
 - [`--use-double-quotes`](template-customization.md#use-double-quotes)
 - [`--use-enum-values-in-discriminator`](field-customization.md#use-enum-values-in-discriminator)
diff --git a/docs/cli-reference/model-customization.md b/docs/cli-reference/model-customization.md
index e0ce2d726..1c00ee367 100644
--- a/docs/cli-reference/model-customization.md
+++ b/docs/cli-reference/model-customization.md
@@ -37,6 +37,7 @@
 | [`--union-mode`](#union-mode) | Union mode for combining anyOf/oneOf schemas (smart or left_... |
 | [`--use-default`](#use-default) | Use default values from schema in generated models. |
 | [`--use-default-factory-for-optional-nested-models`](#use-default-factory-for-optional-nested-models) | Generate default_factory for optional nested model fields. |
+| [`--use-default-keep-required-non-nullable`](#use-default-keep-required-non-nullable) | When using default, keep required field non nullable/non-opt... |
 | [`--use-default-kwarg`](#use-default-kwarg) | Use default= keyword argument instead of positional argument... |
 | [`--use-frozen-field`](#use-frozen-field) | Generate frozen (immutable) field definitions for readOnly p... |
 | [`--use-generic-base-class`](#use-generic-base-class) | Generate a shared base class with model configuration to avo... |
@@ -5292,38 +5293,142 @@ with their defaults, making them optional to provide when instantiating the mode
 
 ??? example "Examples"
 
-    **Input Schema:**
+    === "OpenAPI"
 
-    ```json
-    {
-        "$schema": "http://json-schema.org/draft-07/schema#",
-        "type": "object",
-        "title": "Use default with const",
-        "properties": {
-            "foo": {
-                "const": "foo"
+        **Input Schema:**
+
+        ```yaml
+        openapi: 3.1.0
+        info:
+          title: Data test
+          description: Data test
+        components:
+          schemas:
+            data:
+              type: object
+              required:
+              - number
+              properties:
+                number:
+                  description: Number
+                  default: 1
+                  type: integer
+                  format: int32
+                  minimum: 0
+            block:
+              type: object
+              required:
+              - data
+              properties:
+                data:
+                  $ref: '#/components/schemas/data'
+                dataOptional:
+                  $ref: '#/components/schemas/data'
+        ```
+
+        **Output:**
+
+        === "Pydantic v2"
+
+            ```python
+            # generated by datamodel-codegen:
+            #   filename:  default_factory_keep_required_non_nullable.yaml
+            #   timestamp: 2019-07-26T00:00:00+00:00
+            
+            from __future__ import annotations
+            
+            from pydantic import BaseModel, Field, conint
+            
+            
+            class Data(BaseModel):
+                number: conint(ge=0) = Field(1, description='Number')
+            
+            
+            class Block(BaseModel):
+                data: Data
+                dataOptional: Data | None = None
+            ```
+
+        === "dataclass"
+
+            ```python
+            # generated by datamodel-codegen:
+            #   filename:  default_factory_keep_required_non_nullable.yaml
+            #   timestamp: 2019-07-26T00:00:00+00:00
+            
+            from __future__ import annotations
+            
+            from dataclasses import dataclass
+            
+            
+            @dataclass
+            class Data:
+                number: int = 1
+            
+            
+            @dataclass
+            class Block:
+                data: Data
+                dataOptional: Data | None = None
+            ```
+
+        === "msgspec"
+
+            ```python
+            # generated by datamodel-codegen:
+            #   filename:  default_factory_keep_required_non_nullable.yaml
+            #   timestamp: 2019-07-26T00:00:00+00:00
+            
+            from __future__ import annotations
+            
+            from typing import Annotated
+            
+            from msgspec import UNSET, Meta, Struct, UnsetType
+            
+            
+            class Data(Struct):
+                number: Annotated[int, Meta(description='Number', ge=0)] = 1
+            
+            
+            class Block(Struct):
+                data: Data
+                dataOptional: Data | UnsetType = UNSET
+            ```
+
+    === "JSON Schema"
+
+        **Input Schema:**
+
+        ```json
+        {
+            "$schema": "http://json-schema.org/draft-07/schema#",
+            "type": "object",
+            "title": "Use default with const",
+            "properties": {
+                "foo": {
+                    "const": "foo"
+                }
             }
         }
-    }
-    ```
+        ```
 
-    **Output:**
+        **Output:**
 
-    ```python
-    # generated by datamodel-codegen:
-    #   filename:  use_default_with_const.json
-    #   timestamp: 2019-07-26T00:00:00+00:00
-    
-    from __future__ import annotations
-    
-    from typing import Literal
-    
-    from pydantic import BaseModel
-    
-    
-    class UseDefaultWithConst(BaseModel):
-        foo: Literal['foo'] = 'foo'
-    ```
+        ```python
+        # generated by datamodel-codegen:
+        #   filename:  use_default_with_const.json
+        #   timestamp: 2019-07-26T00:00:00+00:00
+        
+        from __future__ import annotations
+        
+        from typing import Literal
+        
+        from pydantic import BaseModel
+        
+        
+        class UseDefaultWithConst(BaseModel):
+            foo: Literal['foo'] = 'foo'
+        ```
 
 ---
 
@@ -5469,6 +5574,130 @@ for optional nested model fields instead of None default:
 
 ---
 
+## `--use-default-keep-required-non-nullable` {#use-default-keep-required-non-nullable}
+
+When using default, keep required field non nullable/non-optionaloptional.
+
+The `--use-default-keep-required-non-nullable` flag keeps a required field
+as non-nullable/optional:
+- Dataclasses: `field: int = 1`
+- Pydantic: `field: int = 1`
+- msgspec: `field: int = 1`
+
+**Related:** [`--use-default`](model-customization.md#use-default)
+
+!!! tip "Usage"
+
+    ```bash
+    datamodel-codegen --input schema.json --use-default --use-default-keep-required-non-nullable # (1)!
+    ```
+
+    1. :material-arrow-left: `--use-default-keep-required-non-nullable` - the option documented here
+
+??? example "Examples"
+
+    **Input Schema:**
+
+    ```yaml
+    openapi: 3.1.0
+    info:
+      title: Data test
+      description: Data test
+    components:
+      schemas:
+        data:
+          type: object
+          required:
+          - number
+          properties:
+            number:
+              description: Number
+              default: 1
+              type: integer
+              format: int32
+              minimum: 0
+        block:
+          type: object
+          required:
+          - data
+          properties:
+            data:
+              $ref: '#/components/schemas/data'
+            dataOptional:
+              $ref: '#/components/schemas/data'
+    ```
+
+    **Output:**
+
+    === "Pydantic v2"
+
+        ```python
+        # generated by datamodel-codegen:
+        #   filename:  default_factory_keep_required_non_nullable.yaml
+        #   timestamp: 2019-07-26T00:00:00+00:00
+        
+        from __future__ import annotations
+        
+        from pydantic import BaseModel, Field, conint
+        
+        
+        class Data(BaseModel):
+            number: conint(ge=0) = Field(1, description='Number')
+        
+        
+        class Block(BaseModel):
+            data: Data
+            dataOptional: Data | None = None
+        ```
+
+    === "dataclass"
+
+        ```python
+        # generated by datamodel-codegen:
+        #   filename:  default_factory_keep_required_non_nullable.yaml
+        #   timestamp: 2019-07-26T00:00:00+00:00
+        
+        from __future__ import annotations
+        
+        from dataclasses import dataclass
+        
+        
+        @dataclass
+        class Data:
+            number: int = 1
+        
+        
+        @dataclass
+        class Block:
+            data: Data
+            dataOptional: Data | None = None
+        ```
+
+    === "msgspec"
+
+        ```python
+        # generated by datamodel-codegen:
+        #   filename:  default_factory_keep_required_non_nullable.yaml
+        #   timestamp: 2019-07-26T00:00:00+00:00
+        
+        from __future__ import annotations
+        
+        from typing import Annotated
+        
+        from msgspec import UNSET, Meta, Struct, UnsetType
+        
+        
+        class Data(Struct):
+            number: Annotated[int, Meta(description='Number', ge=0)] = 1
+        
+        
+        class Block(Struct):
+            data: Data
+            dataOptional: Data | UnsetType = UNSET
+        ```
+
+---
+
 ## `--use-default-kwarg` {#use-default-kwarg}
 
 Use default= keyword argument instead of positional argument for fields with defaults.
diff --git a/docs/cli-reference/quick-reference.md b/docs/cli-reference/quick-reference.md
index 1308bcc66..094e60c10 100644
--- a/docs/cli-reference/quick-reference.md
+++ b/docs/cli-reference/quick-reference.md
@@ -127,6 +127,7 @@ datamodel-codegen [OPTIONS]
 | [`--union-mode`](model-customization.md#union-mode) | Union mode for combining anyOf/oneOf schemas (smart or left_to_right). |
 | [`--use-default`](model-customization.md#use-default) | Use default values from schema in generated models. |
 | [`--use-default-factory-for-optional-nested-models`](model-customization.md#use-default-factory-for-optional-nested-models) | Generate default_factory for optional nested model fields. |
+| [`--use-default-keep-required-non-nullable`](model-customization.md#use-default-keep-required-non-nullable) | When using default, keep required field non nullable/non-optionaloptional. |
 | [`--use-default-kwarg`](model-customization.md#use-default-kwarg) | Use default= keyword argument instead of positional argument for fields with def... |
 | [`--use-frozen-field`](model-customization.md#use-frozen-field) | Generate frozen (immutable) field definitions for readOnly properties. |
 | [`--use-generic-base-class`](model-customization.md#use-generic-base-class) | Generate a shared base class with model configuration to avoid repetition (DRY). |
@@ -334,6 +335,7 @@ All options sorted alphabetically:
 - [`--use-decimal-for-multiple-of`](typing-customization.md#use-decimal-for-multiple-of) - Generate Decimal types for fields with multipleOf constraint...
 - [`--use-default`](model-customization.md#use-default) - Use default values from schema in generated models.
 - [`--use-default-factory-for-optional-nested-models`](model-customization.md#use-default-factory-for-optional-nested-models) - Generate default_factory for optional nested model fields.
+- [`--use-default-keep-required-non-nullable`](model-customization.md#use-default-keep-required-non-nullable) - When using default, keep required field non nullable/non-opt...
 - [`--use-default-kwarg`](model-customization.md#use-default-kwarg) - Use default= keyword argument instead of positional argument...
 - [`--use-double-quotes`](template-customization.md#use-double-quotes) - Use double quotes for string literals in generated code.
 - [`--use-enum-values-in-discriminator`](field-customization.md#use-enum-values-in-discriminator) - Use enum values in discriminator mappings for union types.
diff --git a/docs/llms-full.txt b/docs/llms-full.txt
index f4226185b..6020c5cfa 100644
--- a/docs/llms-full.txt
+++ b/docs/llms-full.txt
@@ -246,7 +246,7 @@ This documentation is auto-generated from test cases.
 | 📁 [Base Options](base-options.md) | 10 | Input/output configuration |
 | 🔧 [Typing Customization](typing-customization.md) | 29 | Type annotation and import behavior |
 | 🏷️ [Field Customization](field-customization.md) | 24 | Field naming and docstring behavior |
-| 🏗️ [Model Customization](model-customization.md) | 39 | Model generation behavior |
+| 🏗️ [Model Customization](model-customization.md) | 40 | Model generation behavior |
 | 🎨 [Template Customization](template-customization.md) | 21 | Output formatting and custom rendering |
 | 📘 [OpenAPI-only Options](openapi-only-options.md) | 7 | OpenAPI-specific features |
 | 📋 [GraphQL-only Options](graphql-only-options.md) | 1 |  |
@@ -429,6 +429,7 @@ This documentation is auto-generated from test cases.
 - [`--use-decimal-for-multiple-of`](typing-customization.md#use-decimal-for-multiple-of)
 - [`--use-default`](model-customization.md#use-default)
 - [`--use-default-factory-for-optional-nested-models`](model-customization.md#use-default-factory-for-optional-nested-models)
+- [`--use-default-keep-required-non-nullable`](model-customization.md#use-default-keep-required-non-nullable)
 - [`--use-default-kwarg`](model-customization.md#use-default-kwarg)
 - [`--use-double-quotes`](template-customization.md#use-double-quotes)
 - [`--use-enum-values-in-discriminator`](field-customization.md#use-enum-values-in-discriminator)
@@ -1268,6 +1269,7 @@ Source: https://datamodel-code-generator.koxudaxi.dev/cli-reference/model-custom
 | [`--union-mode`](#union-mode) | Union mode for combining anyOf/oneOf schemas (smart or left_... |
 | [`--use-default`](#use-default) | Use default values from schema in generated models. |
 | [`--use-default-factory-for-optional-nested-models`](#use-default-factory-for-optional-nested-models) | Generate default_factory for optional nested model fields. |
+| [`--use-default-keep-required-non-nullable`](#use-default-keep-required-non-nullable) | When using default, keep required field non nullable/non-opt... |
 | [`--use-default-kwarg`](#use-default-kwarg) | Use default= keyword argument instead of positional argument... |
 | [`--use-frozen-field`](#use-frozen-field) | Generate frozen (immutable) field definitions for readOnly p... |
 | [`--use-generic-base-class`](#use-generic-base-class) | Generate a shared base class with model configuration to avo... |
@@ -6523,38 +6525,142 @@ with their defaults, making them optional to provide when instantiating the mode
 
 ??? example "Examples"
 
-    **Input Schema:**
+    === "OpenAPI"
 
-    ```json
-    {
-        "$schema": "http://json-schema.org/draft-07/schema#",
-        "type": "object",
-        "title": "Use default with const",
-        "properties": {
-            "foo": {
-                "const": "foo"
+        **Input Schema:**
+
+        ```yaml
+        openapi: 3.1.0
+        info:
+          title: Data test
+          description: Data test
+        components:
+          schemas:
+            data:
+              type: object
+              required:
+              - number
+              properties:
+                number:
+                  description: Number
+                  default: 1
+                  type: integer
+                  format: int32
+                  minimum: 0
+            block:
+              type: object
+              required:
+              - data
+              properties:
+                data:
+                  $ref: '#/components/schemas/data'
+                dataOptional:
+                  $ref: '#/components/schemas/data'
+        ```
+
+        **Output:**
+
+        === "Pydantic v2"
+
+            ```python
+            # generated by datamodel-codegen:
+            #   filename:  default_factory_keep_required_non_nullable.yaml
+            #   timestamp: 2019-07-26T00:00:00+00:00
+            
+            from __future__ import annotations
+            
+            from pydantic import BaseModel, Field, conint
+            
+            
+            class Data(BaseModel):
+                number: conint(ge=0) = Field(1, description='Number')
+            
+            
+            class Block(BaseModel):
+                data: Data
+                dataOptional: Data | None = None
+            ```
+
+        === "dataclass"
+
+            ```python
+            # generated by datamodel-codegen:
+            #   filename:  default_factory_keep_required_non_nullable.yaml
+            #   timestamp: 2019-07-26T00:00:00+00:00
+            
+            from __future__ import annotations
+            
+            from dataclasses import dataclass
+            
+            
+            @dataclass
+            class Data:
+                number: int = 1
+            
+            
+            @dataclass
+            class Block:
+                data: Data
+                dataOptional: Data | None = None
+            ```
+
+        === "msgspec"
+
+            ```python
+            # generated by datamodel-codegen:
+            #   filename:  default_factory_keep_required_non_nullable.yaml
+            #   timestamp: 2019-07-26T00:00:00+00:00
+            
+            from __future__ import annotations
+            
+            from typing import Annotated
+            
+            from msgspec import UNSET, Meta, Struct, UnsetType
+            
+            
+            class Data(Struct):
+                number: Annotated[int, Meta(description='Number', ge=0)] = 1
+            
+            
+            class Block(Struct):
+                data: Data
+                dataOptional: Data | UnsetType = UNSET
+            ```
+
+    === "JSON Schema"
+
+        **Input Schema:**
+
+        ```json
+        {
+            "$schema": "http://json-schema.org/draft-07/schema#",
+            "type": "object",
+            "title": "Use default with const",
+            "properties": {
+                "foo": {
+                    "const": "foo"
+                }
             }
         }
-    }
-    ```
+        ```
 
-    **Output:**
+        **Output:**
 
-    ```python
-    # generated by datamodel-codegen:
-    #   filename:  use_default_with_const.json
-    #   timestamp: 2019-07-26T00:00:00+00:00
-    
-    from __future__ import annotations
-    
-    from typing import Literal
-    
-    from pydantic import BaseModel
-    
-    
-    class UseDefaultWithConst(BaseModel):
-        foo: Literal['foo'] = 'foo'
-    ```
+        ```python
+        # generated by datamodel-codegen:
+        #   filename:  use_default_with_const.json
+        #   timestamp: 2019-07-26T00:00:00+00:00
+        
+        from __future__ import annotations
+        
+        from typing import Literal
+        
+        from pydantic import BaseModel
+        
+        
+        class UseDefaultWithConst(BaseModel):
+            foo: Literal['foo'] = 'foo'
+        ```
 
 ---
 
@@ -6700,6 +6806,130 @@ for optional nested model fields instead of None default:
 
 ---
 
+## `--use-default-keep-required-non-nullable` {#use-default-keep-required-non-nullable}
+
+When using default, keep required field non nullable/non-optionaloptional.
+
+The `--use-default-keep-required-non-nullable` flag keeps a required field
+as non-nullable/optional:
+- Dataclasses: `field: int = 1`
+- Pydantic: `field: int = 1`
+- msgspec: `field: int = 1`
+
+**Related:** [`--use-default`](model-customization.md#use-default)
+
+!!! tip "Usage"
+
+    ```bash
+    datamodel-codegen --input schema.json --use-default --use-default-keep-required-non-nullable # (1)!
+    ```
+
+    1. :material-arrow-left: `--use-default-keep-required-non-nullable` - the option documented here
+
+??? example "Examples"
+
+    **Input Schema:**
+
+    ```yaml
+    openapi: 3.1.0
+    info:
+      title: Data test
+      description: Data test
+    components:
+      schemas:
+        data:
+          type: object
+          required:
+          - number
+          properties:
+            number:
+              description: Number
+              default: 1
+              type: integer
+              format: int32
+              minimum: 0
+        block:
+          type: object
+          required:
+          - data
+          properties:
+            data:
+              $ref: '#/components/schemas/data'
+            dataOptional:
+              $ref: '#/components/schemas/data'
+    ```
+
+    **Output:**
+
+    === "Pydantic v2"
+
+        ```python
+        # generated by datamodel-codegen:
+        #   filename:  default_factory_keep_required_non_nullable.yaml
+        #   timestamp: 2019-07-26T00:00:00+00:00
+        
+        from __future__ import annotations
+        
+        from pydantic import BaseModel, Field, conint
+        
+        
+        class Data(BaseModel):
+            number: conint(ge=0) = Field(1, description='Number')
+        
+        
+        class Block(BaseModel):
+            data: Data
+            dataOptional: Data | None = None
+        ```
+
+    === "dataclass"
+
+        ```python
+        # generated by datamodel-codegen:
+        #   filename:  default_factory_keep_required_non_nullable.yaml
+        #   timestamp: 2019-07-26T00:00:00+00:00
+        
+        from __future__ import annotations
+        
+        from dataclasses import dataclass
+        
+        
+        @dataclass
+        class Data:
+            number: int = 1
+        
+        
+        @dataclass
+        class Block:
+            data: Data
+            dataOptional: Data | None = None
+        ```
+
+    === "msgspec"
+
+        ```python
+        # generated by datamodel-codegen:
+        #   filename:  default_factory_keep_required_non_nullable.yaml
+        #   timestamp: 2019-07-26T00:00:00+00:00
+        
+        from __future__ import annotations
+        
+        from typing import Annotated
+        
+        from msgspec import UNSET, Meta, Struct, UnsetType
+        
+        
+        class Data(Struct):
+            number: Annotated[int, Meta(description='Number', ge=0)] = 1
+        
+        
+        class Block(Struct):
+            data: Data
+            dataOptional: Data | UnsetType = UNSET
+        ```
+
+---
+
 ## `--use-default-kwarg` {#use-default-kwarg}
 
 Use default= keyword argument instead of positional argument for fields with defaults.
@@ -24032,6 +24262,7 @@ datamodel-codegen [OPTIONS]
 | [`--union-mode`](model-customization.md#union-mode) | Union mode for combining anyOf/oneOf schemas (smart or left_to_right). |
 | [`--use-default`](model-customization.md#use-default) | Use default values from schema in generated models. |
 | [`--use-default-factory-for-optional-nested-models`](model-customization.md#use-default-factory-for-optional-nested-models) | Generate default_factory for optional nested model fields. |
+| [`--use-default-keep-required-non-nullable`](model-customization.md#use-default-keep-required-non-nullable) | When using default, keep required field non nullable/non-optionaloptional. |
 | [`--use-default-kwarg`](model-customization.md#use-default-kwarg) | Use default= keyword argument instead of positional argument for fields with def... |
 | [`--use-frozen-field`](model-customization.md#use-frozen-field) | Generate frozen (immutable) field definitions for readOnly properties. |
 | [`--use-generic-base-class`](model-customization.md#use-generic-base-class) | Generate a shared base class with model configuration to avoid repetition (DRY). |
@@ -24239,6 +24470,7 @@ All options sorted alphabetically:
 - [`--use-decimal-for-multiple-of`](typing-customization.md#use-decimal-for-multiple-of) - Generate Decimal types for fields with multipleOf constraint...
 - [`--use-default`](model-customization.md#use-default) - Use default values from schema in generated models.
 - [`--use-default-factory-for-optional-nested-models`](model-customization.md#use-default-factory-for-optional-nested-models) - Generate default_factory for optional nested model fields.
+- [`--use-default-keep-required-non-nullable`](model-customization.md#use-default-keep-required-non-nullable) - When using default, keep required field non nullable/non-opt...
 - [`--use-default-kwarg`](model-customization.md#use-default-kwarg) - Use default= keyword argument instead of positional argument...
 - [`--use-double-quotes`](template-customization.md#use-double-quotes) - Use double quotes for string literals in generated code.
 - [`--use-enum-values-in-discriminator`](field-customization.md#use-enum-values-in-discriminator) - Use enum values in discriminator mappings for union types.
diff --git a/src/datamodel_code_generator/__main__.py b/src/datamodel_code_generator/__main__.py
index e7225ea13..686b5bfd9 100644
--- a/src/datamodel_code_generator/__main__.py
+++ b/src/datamodel_code_generator/__main__.py
@@ -531,6 +531,7 @@ def validate_class_name_affix_scope(cls, v: str | ClassNameAffixScope | None) ->
     use_serialization_alias: bool = False
     use_frozen_field: bool = False
     use_default_factory_for_optional_nested_models: bool = False
+    use_default_keep_required_non_nullable: bool = False
     formatters: list[Formatter] | None = None
     parent_scoped_naming: bool = False
     naming_strategy: Optional[NamingStrategy] = None  # noqa: UP045
@@ -982,6 +983,7 @@ def run_generate_from_config(  # noqa: PLR0913, PLR0917
         use_serialization_alias=config.use_serialization_alias,
         use_frozen_field=config.use_frozen_field,
         use_default_factory_for_optional_nested_models=config.use_default_factory_for_optional_nested_models,
+        use_default_keep_required_non_nullable=config.use_default_keep_required_non_nullable,
         formatters=config.formatters,
         settings_path=settings_path,
         parent_scoped_naming=config.parent_scoped_naming,
diff --git a/src/datamodel_code_generator/_types/generate_config_dict.py b/src/datamodel_code_generator/_types/generate_config_dict.py
index c0c278d10..750a06a23 100644
--- a/src/datamodel_code_generator/_types/generate_config_dict.py
+++ b/src/datamodel_code_generator/_types/generate_config_dict.py
@@ -156,6 +156,7 @@ class GenerateConfigDict(TypedDict, closed=True):
     use_serialization_alias: NotRequired[bool]
     use_frozen_field: NotRequired[bool]
     use_default_factory_for_optional_nested_models: NotRequired[bool]
+    use_default_keep_required_non_nullable: NotRequired[bool]
     formatters: NotRequired[list[Formatter] | None]
     settings_path: NotRequired[Path | None]
     parent_scoped_naming: NotRequired[bool]
diff --git a/src/datamodel_code_generator/_types/parser_config_dicts.py b/src/datamodel_code_generator/_types/parser_config_dicts.py
index c99912474..9224191e9 100644
--- a/src/datamodel_code_generator/_types/parser_config_dicts.py
+++ b/src/datamodel_code_generator/_types/parser_config_dicts.py
@@ -152,6 +152,7 @@ class ParserConfigDict(TypedDict):
     use_serialization_alias: NotRequired[bool]
     use_frozen_field: NotRequired[bool]
     use_default_factory_for_optional_nested_models: NotRequired[bool]
+    use_default_keep_required_non_nullable: NotRequired[bool]
     formatters: NotRequired[list[Formatter] | None]
     defer_formatting: NotRequired[bool]
     parent_scoped_naming: NotRequired[bool]
diff --git a/src/datamodel_code_generator/arguments.py b/src/datamodel_code_generator/arguments.py
index 7c8f7a7a0..466f22237 100644
--- a/src/datamodel_code_generator/arguments.py
+++ b/src/datamodel_code_generator/arguments.py
@@ -886,6 +886,13 @@ def start_section(self, heading: str | None) -> None:
     action="store_true",
     default=None,
 )
+field_options.add_argument(
+    "--use-default-keep-required-non-nullable",
+    help="When using default, keep required field non nullable/non-optionaloptional."
+    "E.g., `field: int = 1` instead of `field: Model | None = Field(...)`",
+    action="store_true",
+    default=None,
+)
 field_options.add_argument(
     "--field-type-collision-strategy",
     help="Strategy for handling field name and type name collisions (Pydantic v2 only). "
diff --git a/src/datamodel_code_generator/cli_options.py b/src/datamodel_code_generator/cli_options.py
index ad64860d3..6c56127f7 100644
--- a/src/datamodel_code_generator/cli_options.py
+++ b/src/datamodel_code_generator/cli_options.py
@@ -111,6 +111,9 @@ class CLIOptionMeta:
     "--use-default-factory-for-optional-nested-models": CLIOptionMeta(
         name="--use-default-factory-for-optional-nested-models", category=OptionCategory.MODEL
     ),
+    "--use-default-keep-required-non-nullable": CLIOptionMeta(
+        name="--use-default-keep-required-non-nullable", category=OptionCategory.MODEL
+    ),
     "--union-mode": CLIOptionMeta(name="--union-mode", category=OptionCategory.MODEL),
     "--parent-scoped-naming": CLIOptionMeta(
         name="--parent-scoped-naming",
diff --git a/src/datamodel_code_generator/config.py b/src/datamodel_code_generator/config.py
index 4bd1ed9a3..41d6181c0 100644
--- a/src/datamodel_code_generator/config.py
+++ b/src/datamodel_code_generator/config.py
@@ -181,6 +181,7 @@ class GenerateConfig(BaseModel):
     use_serialization_alias: bool = False
     use_frozen_field: bool = False
     use_default_factory_for_optional_nested_models: bool = False
+    use_default_keep_required_non_nullable: bool = False
     formatters: list[Formatter] | None = None
     settings_path: Path | None = None
     parent_scoped_naming: bool = False
@@ -315,6 +316,7 @@ class ParserConfig(BaseModel):
     use_serialization_alias: bool = False
     use_frozen_field: bool = False
     use_default_factory_for_optional_nested_models: bool = False
+    use_default_keep_required_non_nullable: bool = False
     formatters: list[Formatter] | None = None
     defer_formatting: bool = False
     parent_scoped_naming: bool = False
diff --git a/src/datamodel_code_generator/model/base.py b/src/datamodel_code_generator/model/base.py
index 7110f58bc..1cb6dbc6f 100644
--- a/src/datamodel_code_generator/model/base.py
+++ b/src/datamodel_code_generator/model/base.py
@@ -173,6 +173,7 @@ class DataModelFieldBase(_BaseModel):
     use_frozen_field: bool = False
     use_serialization_alias: bool = False
     use_default_factory_for_optional_nested_models: bool = False
+    use_default_keep_required_non_nullable: bool = False
 
     if not TYPE_CHECKING:  # pragma: no branch
 
diff --git a/src/datamodel_code_generator/model/dataclass.py b/src/datamodel_code_generator/model/dataclass.py
index 00040d6d8..befc5d50d 100644
--- a/src/datamodel_code_generator/model/dataclass.py
+++ b/src/datamodel_code_generator/model/dataclass.py
@@ -172,7 +172,7 @@ def __str__(self) -> str:
         if self.default != UNDEFINED and self.default is not None:
             data["default"] = self.default
 
-        if self.required:
+        if self.required and not (self.has_default and self.use_default_keep_required_non_nullable):
             data = {
                 k: v
                 for k, v in data.items()
diff --git a/src/datamodel_code_generator/model/msgspec.py b/src/datamodel_code_generator/model/msgspec.py
index 2119f41d9..4e8ec0e90 100644
--- a/src/datamodel_code_generator/model/msgspec.py
+++ b/src/datamodel_code_generator/model/msgspec.py
@@ -311,7 +311,7 @@ def __str__(self) -> str:  # noqa: PLR0912
         elif self._not_required and "default_factory" not in data:
             data["default"] = None if self.nullable else UNSET
 
-        if self.required:
+        if self.required and not (self.has_default and self.use_default_keep_required_non_nullable):
             data = {
                 k: v
                 for k, v in data.items()
diff --git a/src/datamodel_code_generator/model/pydantic_base.py b/src/datamodel_code_generator/model/pydantic_base.py
index 9c359afb7..0b0b37e8e 100644
--- a/src/datamodel_code_generator/model/pydantic_base.py
+++ b/src/datamodel_code_generator/model/pydantic_base.py
@@ -204,6 +204,8 @@ def __str__(self) -> str:  # noqa: PLR0912
         if not field_arguments and not default_factory:
             if self.nullable and self.required:
                 return "Field(...)"  # Field() is for mypy
+            if self.required and self.has_default and self.use_default_keep_required_non_nullable:
+                return repr_set_sorted(self.default) if isinstance(self.default, set) else repr(self.default)
             return ""
 
         if default_factory:
@@ -211,7 +213,12 @@ def __str__(self) -> str:  # noqa: PLR0912
 
         if self.use_annotated:
             field_arguments = self._process_annotated_field_arguments(field_arguments)
-        elif self.required and not default_factory and not self.extras.get("validate_default"):
+        elif (
+            self.required
+            and not default_factory
+            and not self.extras.get("validate_default")
+            and not (self.has_default and self.use_default_keep_required_non_nullable)
+        ):
             field_arguments = ["...", *field_arguments]
         elif not default_factory:
             default_repr = repr_set_sorted(self.default) if isinstance(self.default, set) else repr(self.default)
@@ -246,7 +253,7 @@ def annotated(self) -> str | None:
     @property
     def imports(self) -> tuple[Import, ...]:
         """Get all required imports including Field if needed."""
-        if self.field:
+        if self.field and self.field.startswith("Field("):
             return chain_as_tuple(super().imports, (IMPORT_FIELD,))
         return super().imports
 
diff --git a/src/datamodel_code_generator/parser/base.py b/src/datamodel_code_generator/parser/base.py
index 73eb59d4f..73e8c049a 100644
--- a/src/datamodel_code_generator/parser/base.py
+++ b/src/datamodel_code_generator/parser/base.py
@@ -1144,6 +1144,7 @@ def __init__(  # noqa: PLR0912, PLR0915
         self.use_default_factory_for_optional_nested_models: bool = (
             config.use_default_factory_for_optional_nested_models
         )
+        self.use_default_keep_required_non_nullable: bool = config.use_default_keep_required_non_nullable
         self.field_type_collision_strategy: FieldTypeCollisionStrategy | None = config.field_type_collision_strategy
 
     @property
diff --git a/src/datamodel_code_generator/parser/graphql.py b/src/datamodel_code_generator/parser/graphql.py
index 82f7e7051..8fb7e57f5 100644
--- a/src/datamodel_code_generator/parser/graphql.py
+++ b/src/datamodel_code_generator/parser/graphql.py
@@ -372,7 +372,11 @@ def parse_field(
             class_name=class_name,
         )
 
-        if self.apply_default_values_for_required_fields and effective_has_default:
+        if (
+            self.apply_default_values_for_required_fields
+            and effective_has_default
+            and not self.use_default_keep_required_non_nullable
+        ):
             required = False
 
         extras = {} if self.default_field_extras is None else self.default_field_extras.copy()
diff --git a/src/datamodel_code_generator/parser/jsonschema.py b/src/datamodel_code_generator/parser/jsonschema.py
index 34ee95f3c..8b1111934 100644
--- a/src/datamodel_code_generator/parser/jsonschema.py
+++ b/src/datamodel_code_generator/parser/jsonschema.py
@@ -694,10 +694,8 @@ def __init__(
         self._circular_ref_cache: dict[str, bool] = {}
 
         if self.data_model_field_type.can_have_extra_keys:
-            self.get_field_extra_key: Callable[[str], str] = (
-                lambda key: self.model_resolver.get_valid_field_name_and_alias(
-                    key, model_type=self.field_name_model_type
-                )[0]
+            self.get_field_extra_key: Callable[[str], str] = lambda key: (
+                self.model_resolver.get_valid_field_name_and_alias(key, model_type=self.field_name_model_type)[0]
             )
 
         else:
@@ -1252,6 +1250,7 @@ def get_object_field(  # noqa: PLR0913
             use_frozen_field=self.use_frozen_field,
             use_serialization_alias=self.use_serialization_alias,
             use_default_factory_for_optional_nested_models=self.use_default_factory_for_optional_nested_models,
+            use_default_keep_required_non_nullable=self.use_default_keep_required_non_nullable,
         )
 
     def get_data_type(self, obj: JsonSchemaObject) -> DataType:
@@ -2830,11 +2829,14 @@ def parse_object_fields(
             )
 
             if self.force_optional_for_required_fields or (
-                self.apply_default_values_for_required_fields and effective_has_default
+                self.apply_default_values_for_required_fields
+                and effective_has_default
+                and not self.use_default_keep_required_non_nullable
             ):
                 required: bool = False
             else:
                 required = original_field_name in requires
+
             fields.append(
                 self.get_object_field(
                     field_name=field_name,
diff --git a/src/datamodel_code_generator/parser/openapi.py b/src/datamodel_code_generator/parser/openapi.py
index 2e30a46b1..be994e44a 100644
--- a/src/datamodel_code_generator/parser/openapi.py
+++ b/src/datamodel_code_generator/parser/openapi.py
@@ -551,7 +551,11 @@ def parse_all_parameters(  # noqa: PLR0912, PLR0914, PLR0915
                     class_name=reference.name,
                 )
                 effective_required = parameter.required
-                if self.apply_default_values_for_required_fields and effective_has_default:
+                if (
+                    self.apply_default_values_for_required_fields
+                    and effective_has_default
+                    and not self.use_default_keep_required_non_nullable
+                ):
                     effective_required = False
                 fields.append(
                     self.get_object_field(
@@ -600,7 +604,11 @@ def parse_all_parameters(  # noqa: PLR0912, PLR0914, PLR0915
                     class_name=reference.name,
                 )
                 effective_required = parameter.required
-                if self.apply_default_values_for_required_fields and effective_has_default:
+                if (
+                    self.apply_default_values_for_required_fields
+                    and effective_has_default
+                    and not self.use_default_keep_required_non_nullable
+                ):
                     effective_required = False
                 # Handle multiple aliases (Pydantic v2 AliasChoices)
                 single_alias: str | None = None
diff --git a/src/datamodel_code_generator/prompt_data.py b/src/datamodel_code_generator/prompt_data.py
index 32fae3512..4a7190d71 100644
--- a/src/datamodel_code_generator/prompt_data.py
+++ b/src/datamodel_code_generator/prompt_data.py
@@ -120,6 +120,7 @@
     "--use-decimal-for-multiple-of": "Generate Decimal types for fields with multipleOf constraint.",
     "--use-default": "Use default values from schema in generated models.",
     "--use-default-factory-for-optional-nested-models": "Generate default_factory for optional nested model fields.",
+    "--use-default-keep-required-non-nullable": "When using default, keep required field non nullable/non-optionaloptional.",
     "--use-default-kwarg": "Use default= keyword argument instead of positional argument for fields with defaults.",
     "--use-double-quotes": "Use double quotes for string literals in generated code.",
     "--use-enum-values-in-discriminator": "Use enum values in discriminator mappings for union types.",
diff --git a/tests/data/expected/main/input_model/config_class.py b/tests/data/expected/main/input_model/config_class.py
index 02437ce39..0472b03f5 100644
--- a/tests/data/expected/main/input_model/config_class.py
+++ b/tests/data/expected/main/input_model/config_class.py
@@ -235,6 +235,7 @@ class GenerateConfig(TypedDict, closed=True):
     use_serialization_alias: NotRequired[bool]
     use_frozen_field: NotRequired[bool]
     use_default_factory_for_optional_nested_models: NotRequired[bool]
+    use_default_keep_required_non_nullable: NotRequired[bool]
     formatters: NotRequired[list[Formatter] | None]
     settings_path: NotRequired[str | None]
     parent_scoped_naming: NotRequired[bool]
diff --git a/tests/data/expected/main/openapi/default_keep_required_non_nullable_dataclass.py b/tests/data/expected/main/openapi/default_keep_required_non_nullable_dataclass.py
new file mode 100644
index 000000000..f0307030d
--- /dev/null
+++ b/tests/data/expected/main/openapi/default_keep_required_non_nullable_dataclass.py
@@ -0,0 +1,18 @@
+# generated by datamodel-codegen:
+#   filename:  default_factory_keep_required_non_nullable.yaml
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+
+@dataclass
+class Data:
+    number: int = 1
+
+
+@dataclass
+class Block:
+    data: Data
+    dataOptional: Data | None = None
diff --git a/tests/data/expected/main/openapi/default_keep_required_non_nullable_msgspec.py b/tests/data/expected/main/openapi/default_keep_required_non_nullable_msgspec.py
new file mode 100644
index 000000000..0723985b3
--- /dev/null
+++ b/tests/data/expected/main/openapi/default_keep_required_non_nullable_msgspec.py
@@ -0,0 +1,18 @@
+# generated by datamodel-codegen:
+#   filename:  default_factory_keep_required_non_nullable.yaml
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from typing import Annotated
+
+from msgspec import UNSET, Meta, Struct, UnsetType
+
+
+class Data(Struct):
+    number: Annotated[int, Meta(description='Number', ge=0)] = 1
+
+
+class Block(Struct):
+    data: Data
+    dataOptional: Data | UnsetType = UNSET
diff --git a/tests/data/expected/main/openapi/default_keep_required_non_nullable_pydantic_v2.py b/tests/data/expected/main/openapi/default_keep_required_non_nullable_pydantic_v2.py
new file mode 100644
index 000000000..a3bab398c
--- /dev/null
+++ b/tests/data/expected/main/openapi/default_keep_required_non_nullable_pydantic_v2.py
@@ -0,0 +1,16 @@
+# generated by datamodel-codegen:
+#   filename:  default_factory_keep_required_non_nullable.yaml
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from pydantic import BaseModel, Field, conint
+
+
+class Data(BaseModel):
+    number: conint(ge=0) = Field(1, description='Number')
+
+
+class Block(BaseModel):
+    data: Data
+    dataOptional: Data | None = None
diff --git a/tests/data/expected/main/openapi/use_default_keep_required_non_nullable.py b/tests/data/expected/main/openapi/use_default_keep_required_non_nullable.py
new file mode 100644
index 000000000..d8f4c79aa
--- /dev/null
+++ b/tests/data/expected/main/openapi/use_default_keep_required_non_nullable.py
@@ -0,0 +1,67 @@
+# generated by datamodel-codegen:
+#   filename:  api.yaml
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from pydantic import AnyUrl, BaseModel, Field, RootModel
+
+
+class Pet(BaseModel):
+    id: int = 1
+    name: str
+    tag: str | None = None
+
+
+class Pets(RootModel[list[Pet]]):
+    root: list[Pet]
+
+
+class User(BaseModel):
+    id: int
+    name: str
+    tag: str | None = None
+
+
+class Users(RootModel[list[User]]):
+    root: list[User]
+
+
+class Id(RootModel[str]):
+    root: str
+
+
+class Rules(RootModel[list[str]]):
+    root: list[str]
+
+
+class Error(BaseModel):
+    code: int
+    message: str
+
+
+class Api(BaseModel):
+    apiKey: str | None = Field(
+        None, description='To be used as a dataset parameter value'
+    )
+    apiVersionNumber: str | None = Field(
+        None, description='To be used as a version parameter value'
+    )
+    apiUrl: AnyUrl | None = Field(
+        None, description="The URL describing the dataset's fields"
+    )
+    apiDocumentationUrl: AnyUrl | None = Field(
+        None, description='A URL to the API console for each API'
+    )
+
+
+class Apis(RootModel[list[Api]]):
+    root: list[Api]
+
+
+class Event(BaseModel):
+    name: str | None = None
+
+
+class Result(BaseModel):
+    event: Event | None = None
diff --git a/tests/data/openapi/default_factory_keep_required_non_nullable.yaml b/tests/data/openapi/default_factory_keep_required_non_nullable.yaml
new file mode 100644
index 000000000..6295c23af
--- /dev/null
+++ b/tests/data/openapi/default_factory_keep_required_non_nullable.yaml
@@ -0,0 +1,26 @@
+openapi: 3.1.0
+info:
+  title: Data test
+  description: Data test
+components:
+  schemas:
+    data:
+      type: object
+      required:
+      - number
+      properties:
+        number:
+          description: Number
+          default: 1
+          type: integer
+          format: int32
+          minimum: 0
+    block:
+      type: object
+      required:
+      - data
+      properties:
+        data:
+          $ref: '#/components/schemas/data'
+        dataOptional:
+          $ref: '#/components/schemas/data'
diff --git a/tests/main/openapi/test_main_openapi.py b/tests/main/openapi/test_main_openapi.py
index 65121180d..b0b8a8b0b 100644
--- a/tests/main/openapi/test_main_openapi.py
+++ b/tests/main/openapi/test_main_openapi.py
@@ -743,7 +743,8 @@ def get_path(path: str) -> str:
     output_file: Path = tmp_path / "output.py"
     pyproject_toml_path = Path(DATA_PATH) / "project" / "pyproject.toml"
     pyproject_toml = (
-        pyproject_toml_path.read_text()
+        pyproject_toml_path
+        .read_text()
         .replace("INPUT_PATH", get_path(OPEN_API_DATA_PATH / "api.yaml"))
         .replace("OUTPUT_PATH", get_path(output_file))
         .replace("ALIASES_PATH", get_path(OPEN_API_DATA_PATH / "empty_aliases.json"))
@@ -5316,3 +5317,73 @@ def test_main_reuse_model_with_type_alias(output_file: Path) -> None:
             "--use-type-alias",
         ],
     )
+
+
+@pytest.mark.benchmark
+def test_use_default_keep_required_non_nullable(output_file: Path) -> None:
+    """Test OpenAPI generation with use default option."""
+    run_main_and_assert(
+        input_path=OPEN_API_DATA_PATH / "api.yaml",
+        output_path=output_file,
+        input_file_type=None,
+        assert_func=assert_file_content,
+        extra_args=[
+            "--use-default",
+            "--use-default-keep-required-non-nullable",
+        ],
+    )
+
+
+@pytest.mark.parametrize(
+    ("output_model", "expected_file"),
+    [
+        ("dataclasses.dataclass", "default_keep_required_non_nullable_dataclass.py"),
+        ("pydantic_v2.BaseModel", "default_keep_required_non_nullable_pydantic_v2.py"),
+        ("msgspec.Struct", "default_keep_required_non_nullable_msgspec.py"),
+    ],
+)
+@pytest.mark.cli_doc(
+    options=["--use-default", "--use-default-keep-required-non-nullable"],
+    option_description="""When using default, keep required field non nullable/non-optionaloptional.
+
+The `--use-default-keep-required-non-nullable` flag keeps a required field
+as non-nullable/optional:
+- Dataclasses: `field: int = 1`
+- Pydantic: `field: int = 1`
+- msgspec: `field: int = 1`""",
+    input_schema="openapi/default_factory_keep_required_non_nullable.yaml",
+    cli_args=[
+        "--use-default",
+        "--use-default-keep-required-non-nullable",
+    ],
+    related_options=["--use-default"],
+    model_outputs={
+        "dataclass": "main/openapi/default_keep_required_non_nullable_dataclass.py",
+        "pydantic_v2": "main/openapi/default_keep_required_non_nullable_pydantic_v2.py",
+        "msgspec": "main/openapi/default_keep_required_non_nullable_msgspec.py",
+    },
+)
+@pytest.mark.benchmark
+@LEGACY_BLACK_SKIP
+def test_main_use_default_keep_required_non_nullable(output_model: str, expected_file: str, output_file: Path) -> None:
+    """When using default, keep required field non nullable/non-optionaloptional.
+
+    The `--use-default-keep-required-non-nullable` flag keeps a required field
+    as non-nullable/optional:
+    - Dataclasses: `field: int = 1`
+    - Pydantic: `field: int = 1`
+    - msgspec: `field: int = 1`
+    """
+    run_main_and_assert(
+        input_path=OPEN_API_DATA_PATH / "default_factory_keep_required_non_nullable.yaml",
+        output_path=output_file,
+        input_file_type="openapi",
+        assert_func=assert_file_content,
+        expected_file=expected_file,
+        extra_args=[
+            "--output-model-type",
+            output_model,
+            "--use-default",
+            "--use-default-keep-required-non-nullable",
+        ],
+    )
diff --git a/tests/main/test_public_api_signature_baseline.py b/tests/main/test_public_api_signature_baseline.py
index b5511a070..b0ac33d44 100644
--- a/tests/main/test_public_api_signature_baseline.py
+++ b/tests/main/test_public_api_signature_baseline.py
@@ -171,6 +171,7 @@ def _baseline_generate(
     use_serialization_alias: bool = False,
     use_frozen_field: bool = False,
     use_default_factory_for_optional_nested_models: bool = False,
+    use_default_keep_required_non_nullable: bool = False,
     formatters: list[Formatter] | None = None,
     settings_path: Path | None = None,
     parent_scoped_naming: bool = False,
@@ -307,6 +308,7 @@ def __init__(
         use_serialization_alias: bool = False,
         use_frozen_field: bool = False,
         use_default_factory_for_optional_nested_models: bool = False,
+        use_default_keep_required_non_nullable: bool = False,
         formatters: list[Formatter] | None = None,
         defer_formatting: bool = False,
         parent_scoped_naming: bool = False,