diff --git a/.changeset/honest-news-create.md b/.changeset/honest-news-create.md
new file mode 100644
index 000000000..d32e4c31d
--- /dev/null
+++ b/.changeset/honest-news-create.md
@@ -0,0 +1,5 @@
+---
+'@livekit/agents-plugin-openai': patch
+---
+
+Add Reasoning param for gpt-realtime-2\* model family
diff --git a/plugins/openai/src/realtime/api_proto.ts b/plugins/openai/src/realtime/api_proto.ts
index 1d4c775c8..df003e483 100644
--- a/plugins/openai/src/realtime/api_proto.ts
+++ b/plugins/openai/src/realtime/api_proto.ts
@@ -10,6 +10,20 @@ export const OUT_FRAME_SIZE = 1200; // 50ms
 export const BASE_URL = 'wss://api.openai.com/v1';
 
 export type Model = 'gpt-4o-realtime-preview-2024-10-01' | string; // Open-ended, for future models
+
+/**
+ * Models that support the `reasoning` configuration on the Realtime API.
+ * Currently only the `gpt-realtime-2` family supports it.
+ *
+ * Ref: https://developers.openai.com/api/reference/resources/realtime/subresources/calls/methods/accept
+ */
+export type ReasoningCapableModel = 'gpt-realtime-2' | `gpt-realtime-2-${string}`;
+
+export type ReasoningEffort = 'minimal' | 'low' | 'medium' | 'high' | 'xhigh';
+
+export interface Reasoning {
+  effort?: ReasoningEffort;
+}
 export type Voice =
   | 'alloy'
   | 'shimmer'
@@ -328,6 +342,7 @@ export interface SessionUpdateEvent extends BaseClientEvent {
     audio?: RealtimeAudioConfig; // GA: nested audio config
     max_output_tokens?: number | 'inf'; // GA: renamed from max_response_output_tokens
     tracing?: TracingConfig | null; // GA: tracing config
+    reasoning?: Reasoning | null; // GA: reasoning config (gpt-realtime-2 only)
     // Common fields
     model: Model;
     instructions: string;
diff --git a/plugins/openai/src/realtime/realtime_model.ts b/plugins/openai/src/realtime/realtime_model.ts
index 662448112..d3987447b 100644
--- a/plugins/openai/src/realtime/realtime_model.ts
+++ b/plugins/openai/src/realtime/realtime_model.ts
@@ -48,6 +48,7 @@ interface RealtimeOptions {
   maxResponseOutputTokens?: number | 'inf';
   speed?: number;
   tracing?: api_proto.TracingConfig | null;
+  reasoning?: api_proto.Reasoning;
   apiKey?: string;
   baseURL: string;
   isAzure: boolean;
@@ -158,8 +159,10 @@ export class RealtimeModel extends llm.RealtimeModel {
   }
 
   constructor(
-    options: {
-      model?: string;
+    options: (
+      | { model: api_proto.ReasoningCapableModel; reasoning?: api_proto.Reasoning }
+      | { model?: string; reasoning?: never }
+    ) & {
       voice?: string;
       /** @deprecated Unused in GA API (v1). Temperature is no longer supported. */
       temperature?: number;
@@ -514,6 +517,7 @@ export class RealtimeSession extends llm.RealtimeSession {
     // GA format (OpenAI or Azure GA)
     const audioFormat: api_proto.AudioFormat = { type: 'audio/pcm', rate: SAMPLE_RATE };
     const modality: Modality = opts.modalities.includes('audio') ? 'audio' : 'text';
+    const includeReasoning = opts.reasoning && opts.model.startsWith('gpt-realtime-2');
     return {
       type: 'session.update',
       session: {
@@ -537,6 +541,7 @@ export class RealtimeSession extends llm.RealtimeSession {
         tool_choice: toOaiToolChoice(opts.toolChoice),
         tracing: opts.tracing,
         instructions: this.instructions,
+        ...(includeReasoning ? { reasoning: opts.reasoning } : {}),
       },
     };
   }