diff --git a/.changeset/quiet-dodos-smile.md b/.changeset/quiet-dodos-smile.md
new file mode 100644
index 0000000000..6bd74471f5
--- /dev/null
+++ b/.changeset/quiet-dodos-smile.md
@@ -0,0 +1,5 @@
+---
+'@livekit/agents-plugin-gradium': patch
+---
+
+Honor voice ID updates and use Harper as the default Gradium TTS voice.
diff --git a/plugins/gradium/src/tts.ts b/plugins/gradium/src/tts.ts
index 747b45333a..a84c861763 100644
--- a/plugins/gradium/src/tts.ts
+++ b/plugins/gradium/src/tts.ts
@@ -72,7 +72,7 @@ function resolveOptions(opts: Partial<TTSOptions>): ResolvedTTSOptions {
     modelEndpoint,
     modelName: opts.modelName ?? 'default',
     voice: opts.voice,
-    voiceId: opts.voiceId ?? 'YTpq7expH9539ERJ',
+    voiceId: opts.voiceId ?? '4SZHfMpw-p46Ywgs',
     pronunciationId: opts.pronunciationId,
     jsonConfig: opts.jsonConfig,
     wordTokenizer: opts.wordTokenizer ?? new tokenize.basic.WordTokenizer(false),
@@ -147,7 +147,7 @@ export class TTS extends tts.TTS {
     return 'Gradium';
   }
 
-  updateOptions(opts: Partial<Pick<TTSOptions, 'voice' | 'jsonConfig'>>) {
+  updateOptions(opts: Partial<Pick<TTSOptions, 'voice' | 'voiceId' | 'jsonConfig'>>) {
     this.#opts = { ...this.#opts, ...opts };
   }