diff --git a/extensions/matrix/src/matrix/sdk.test.ts b/extensions/matrix/src/matrix/sdk.test.ts
index d76dcbdb2c3..b5170fba545 100644
--- a/extensions/matrix/src/matrix/sdk.test.ts
+++ b/extensions/matrix/src/matrix/sdk.test.ts
@@ -255,6 +255,75 @@ describe("MatrixClient request hardening", () => {
     });
   });
 
+  it("serializes outbound sends per room across message and event sends", async () => {
+    const client = new MatrixClient("https://matrix.example.org", "token");
+    let releaseFirst: (() => void) | undefined;
+    const started: string[] = [];
+    matrixJsClient.sendMessage = vi.fn(async () => {
+      started.push("message");
+      await new Promise<void>((resolve) => {
+        releaseFirst = resolve;
+      });
+      return { event_id: "$message" };
+    });
+    matrixJsClient.sendEvent = vi.fn(async () => {
+      started.push("event");
+      return { event_id: "$event" };
+    });
+
+    const first = client.sendMessage("!room:example.org", {
+      msgtype: "m.text",
+      body: "hello",
+    });
+    const second = client.sendEvent("!room:example.org", "m.reaction", {
+      "m.relates_to": { event_id: "$target", key: "👍", rel_type: "m.annotation" },
+    });
+
+    await Promise.resolve();
+    await Promise.resolve();
+    expect(started).toEqual(["message"]);
+    expect(matrixJsClient.sendEvent).not.toHaveBeenCalled();
+
+    releaseFirst?.();
+
+    await expect(first).resolves.toBe("$message");
+    await expect(second).resolves.toBe("$event");
+    expect(started).toEqual(["message", "event"]);
+  });
+
+  it("does not serialize sends across different rooms", async () => {
+    const client = new MatrixClient("https://matrix.example.org", "token");
+    let releaseFirst: (() => void) | undefined;
+    const started: string[] = [];
+    matrixJsClient.sendMessage = vi.fn(async (roomId: string) => {
+      started.push(roomId);
+      if (roomId === "!room-a:example.org") {
+        await new Promise<void>((resolve) => {
+          releaseFirst = resolve;
+        });
+      }
+      return { event_id: `$${roomId}` };
+    });
+
+    const first = client.sendMessage("!room-a:example.org", {
+      msgtype: "m.text",
+      body: "a",
+    });
+    const second = client.sendMessage("!room-b:example.org", {
+      msgtype: "m.text",
+      body: "b",
+    });
+
+    await Promise.resolve();
+    await Promise.resolve();
+    expect(started).toEqual(["!room-a:example.org", "!room-b:example.org"]);
+
+    releaseFirst?.();
+
+    await expect(first).resolves.toBe("$!room-a:example.org");
+    await expect(second).resolves.toBe("$!room-b:example.org");
+  });
+
   it("maps relations pages back to raw events", async () => {
     const client = new MatrixClient("https://matrix.example.org", "token");
     matrixJsClient.relations = vi.fn(async () => ({
diff --git a/extensions/matrix/src/matrix/sdk.ts b/extensions/matrix/src/matrix/sdk.ts
index 1a8c220d6ec..31aa518ba87 100644
--- a/extensions/matrix/src/matrix/sdk.ts
+++ b/extensions/matrix/src/matrix/sdk.ts
@@ -9,6 +9,7 @@ import {
   type MatrixEvent,
 } from "matrix-js-sdk";
 import { VerificationMethod } from "matrix-js-sdk/lib/types.js";
+import { KeyedAsyncQueue } from "openclaw/plugin-sdk/keyed-async-queue";
 import { resolveMatrixRoomKeyBackupReadinessError } from "./backup-health.js";
 import { createMatrixJsSdkClientLogger } from "./client/logging.js";
 import { MatrixCryptoBootstrapper } from "./sdk/crypto-bootstrap.js";
@@ -169,6 +170,7 @@ export class MatrixClient {
   private cryptoInitialized = false;
   private readonly decryptBridge: MatrixDecryptBridge<MatrixRawEvent>;
   private readonly verificationManager = new MatrixVerificationManager();
+  private readonly sendQueue = new KeyedAsyncQueue();
   private readonly recoveryKeyStore: MatrixRecoveryKeyStore;
   private readonly cryptoBootstrapper: MatrixCryptoBootstrapper<MatrixRawEvent>;
   private readonly autoBootstrapCrypto: boolean;
@@ -526,8 +528,10 @@ export class MatrixClient {
   }
 
   async sendMessage(roomId: string, content: MessageEventContent): Promise<string> {
-    const sent = await this.client.sendMessage(roomId, content as never);
-    return sent.event_id;
+    return await this.runSerializedRoomSend(roomId, async () => {
+      const sent = await this.client.sendMessage(roomId, content as never);
+      return sent.event_id;
+    });
   }
 
   async sendEvent(
@@ -535,8 +539,16 @@ export class MatrixClient {
     eventType: string,
     content: Record<string, unknown>,
   ): Promise<string> {
-    const sent = await this.client.sendEvent(roomId, eventType as never, content as never);
-    return sent.event_id;
+    return await this.runSerializedRoomSend(roomId, async () => {
+      const sent = await this.client.sendEvent(roomId, eventType as never, content as never);
+      return sent.event_id;
+    });
+  }
+
+  // Keep outbound room events ordered when multiple plugin paths emit
+  // messages/reactions/polls into the same Matrix room concurrently.
+  private async runSerializedRoomSend<T>(roomId: string, task: () => Promise<T>): Promise<T> {
+    return await this.sendQueue.enqueue(roomId, task);
   }
 
   async sendStateEvent(