diff --git a/.changeset/deepgram-redact-param.md b/.changeset/deepgram-redact-param.md
new file mode 100644
index 000000000..a31091650
--- /dev/null
+++ b/.changeset/deepgram-redact-param.md
@@ -0,0 +1,5 @@
+---
+'@livekit/agents-plugin-deepgram': patch
+---
+
+Avoid serializing an unset Deepgram STT redact query parameter.
diff --git a/plugins/deepgram/src/stt.ts b/plugins/deepgram/src/stt.ts
index 3f2650b56..922e28b71 100644
--- a/plugins/deepgram/src/stt.ts
+++ b/plugins/deepgram/src/stt.ts
@@ -267,9 +267,9 @@ export class SpeechStream extends stt.SpeechStream {
         keywords: this.#opts.keywords.map((x) => x.join(':')),
         keyterm: this.#opts.keyterm,
         profanity_filter: this.#opts.profanityFilter,
-        redact: this.#opts.redact,
         language: this.#opts.language,
         mip_opt_out: this.#opts.mipOptOut,
+        ...(this.#opts.redact.length > 0 ? { redact: this.#opts.redact } : {}),
       };
       Object.entries(params).forEach(([k, v]) => {
         if (v !== undefined) {