diff --git a/extensions/matrix/src/matrix/client.test.ts b/extensions/matrix/src/matrix/client.test.ts
index b3092f60a24..5933c77dd7a 100644
--- a/extensions/matrix/src/matrix/client.test.ts
+++ b/extensions/matrix/src/matrix/client.test.ts
@@ -6,6 +6,7 @@ import {
   resolveMatrixAuthContext,
   resolveMatrixConfig,
   resolveMatrixConfigForAccount,
+  validateMatrixHomeserverUrl,
 } from "./client.js";
 import * as credentialsModule from "./credentials.js";
 import * as sdkModule from "./sdk.js";
@@ -146,6 +147,13 @@ describe("resolveMatrixConfig", () => {
       "default",
     );
   });
+
+  it("rejects insecure public http Matrix homeservers", () => {
+    expect(() => validateMatrixHomeserverUrl("http://matrix.example.org")).toThrow(
+      "Matrix homeserver must use https:// unless it targets a private or loopback host",
+    );
+    expect(validateMatrixHomeserverUrl("http://127.0.0.1:8008")).toBe("http://127.0.0.1:8008");
+  });
 });
 
 describe("resolveMatrixAuth", () => {
@@ -273,6 +281,21 @@ describe("resolveMatrixAuth", () => {
     expect(saveMatrixCredentialsMock).not.toHaveBeenCalled();
   });
 
+  it("rejects embedded credentials in Matrix homeserver URLs", async () => {
+    const cfg = {
+      channels: {
+        matrix: {
+          homeserver: "https://user:pass@matrix.example.org",
+          accessToken: "tok-123",
+        },
+      },
+    } as CoreConfig;
+
+    await expect(resolveMatrixAuth({ cfg, env: {} as NodeJS.ProcessEnv })).rejects.toThrow(
+      "Matrix homeserver URL must not include embedded credentials",
+    );
+  });
+
   it("falls back to config deviceId when cached credentials are missing it", async () => {
     vi.mocked(credentialsModule.loadMatrixCredentials).mockReturnValue({
       homeserver: "https://matrix.example.org",
diff --git a/extensions/matrix/src/matrix/client.ts b/extensions/matrix/src/matrix/client.ts
index 91a91cb3cae..887b49f9799 100644
--- a/extensions/matrix/src/matrix/client.ts
+++ b/extensions/matrix/src/matrix/client.ts
@@ -9,6 +9,7 @@ export {
   resolveImplicitMatrixAccountId,
   resolveMatrixAuth,
   resolveMatrixAuthContext,
+  validateMatrixHomeserverUrl,
 } from "./client/config.js";
 export { createMatrixClient } from "./client/create-client.js";
 export {
diff --git a/extensions/matrix/src/matrix/client/config.ts b/extensions/matrix/src/matrix/client/config.ts
index 147e1ab69f3..c06a2c563c3 100644
--- a/extensions/matrix/src/matrix/client/config.ts
+++ b/extensions/matrix/src/matrix/client/config.ts
@@ -1,8 +1,9 @@
 import {
   DEFAULT_ACCOUNT_ID,
+  isPrivateOrLoopbackHost,
   normalizeAccountId,
   normalizeOptionalAccountId,
-} from "openclaw/plugin-sdk/account-id";
+} from "openclaw/plugin-sdk/matrix";
 import { getMatrixRuntime } from "../../runtime.js";
 import { normalizeResolvedSecretInputString } from "../../secret-input.js";
 import type { CoreConfig } from "../../types.js";
@@ -142,6 +143,40 @@ export function hasReadyMatrixEnvAuth(config: {
   return Boolean(homeserver && (accessToken || (userId && password)));
 }
 
+export function validateMatrixHomeserverUrl(homeserver: string): string {
+  const trimmed = clean(homeserver, "matrix.homeserver");
+  if (!trimmed) {
+    throw new Error("Matrix homeserver is required (matrix.homeserver)");
+  }
+
+  let parsed: URL;
+  try {
+    parsed = new URL(trimmed);
+  } catch {
+    throw new Error("Matrix homeserver must be a valid http(s) URL");
+  }
+
+  if (parsed.protocol !== "https:" && parsed.protocol !== "http:") {
+    throw new Error("Matrix homeserver must use http:// or https://");
+  }
+  if (!parsed.hostname) {
+    throw new Error("Matrix homeserver must include a hostname");
+  }
+  if (parsed.username || parsed.password) {
+    throw new Error("Matrix homeserver URL must not include embedded credentials");
+  }
+  if (parsed.search || parsed.hash) {
+    throw new Error("Matrix homeserver URL must not include query strings or fragments");
+  }
+  if (parsed.protocol === "http:" && !isPrivateOrLoopbackHost(parsed.hostname)) {
+    throw new Error(
+      "Matrix homeserver must use https:// unless it targets a private or loopback host",
+    );
+  }
+
+  return trimmed;
+}
+
 export function resolveMatrixConfig(
   cfg: CoreConfig = getMatrixRuntime().config.loadConfig() as CoreConfig,
   env: NodeJS.ProcessEnv = process.env,
@@ -346,9 +381,7 @@ export async function resolveMatrixAuth(params?: {
   accountId?: string | null;
 }): Promise<MatrixAuth> {
   const { cfg, env, accountId, resolved } = resolveMatrixAuthContext(params);
-  if (!resolved.homeserver) {
-    throw new Error("Matrix homeserver is required (matrix.homeserver)");
-  }
+  const homeserver = validateMatrixHomeserverUrl(resolved.homeserver);
 
   const {
     loadMatrixCredentials,
@@ -361,7 +394,7 @@ export async function resolveMatrixAuth(params?: {
   const cachedCredentials =
     cached &&
     credentialsMatchConfig(cached, {
-      homeserver: resolved.homeserver,
+      homeserver,
       userId: resolved.userId || "",
       accessToken: resolved.accessToken,
     })
@@ -379,7 +412,7 @@ export async function resolveMatrixAuth(params?: {
     if (!userId || !knownDeviceId) {
       // Fetch whoami when we need to resolve userId and/or deviceId from token auth.
       ensureMatrixSdkLoggingConfigured();
-      const tempClient = new MatrixClient(resolved.homeserver, resolved.accessToken);
+      const tempClient = new MatrixClient(homeserver, resolved.accessToken);
       const whoami = (await tempClient.doRequest("GET", "/_matrix/client/v3/account/whoami")) as {
         user_id?: string;
         device_id?: string;
@@ -404,7 +437,7 @@ export async function resolveMatrixAuth(params?: {
     if (shouldRefreshCachedCredentials) {
       await saveMatrixCredentials(
         {
-          homeserver: resolved.homeserver,
+          homeserver,
           userId,
           accessToken: resolved.accessToken,
           deviceId: knownDeviceId,
@@ -417,7 +450,7 @@ export async function resolveMatrixAuth(params?: {
     }
     return {
       accountId,
-      homeserver: resolved.homeserver,
+      homeserver,
       userId,
       accessToken: resolved.accessToken,
       password: resolved.password,
@@ -455,7 +488,7 @@ export async function resolveMatrixAuth(params?: {
 
   // Login with password using the same hardened request path as other Matrix HTTP calls.
   ensureMatrixSdkLoggingConfigured();
-  const loginClient = new MatrixClient(resolved.homeserver, "");
+  const loginClient = new MatrixClient(homeserver, "");
   const login = (await loginClient.doRequest("POST", "/_matrix/client/v3/login", undefined, {
     type: "m.login.password",
     identifier: { type: "m.id.user", user: resolved.userId },
@@ -475,7 +508,7 @@ export async function resolveMatrixAuth(params?: {
 
   const auth: MatrixAuth = {
     accountId,
-    homeserver: resolved.homeserver,
+    homeserver,
     userId: login.user_id ?? resolved.userId,
     accessToken,
     password: resolved.password,
diff --git a/extensions/matrix/src/matrix/client/create-client.ts b/extensions/matrix/src/matrix/client/create-client.ts
index 0d290a0a794..1c66dbbc302 100644
--- a/extensions/matrix/src/matrix/client/create-client.ts
+++ b/extensions/matrix/src/matrix/client/create-client.ts
@@ -1,5 +1,6 @@
 import fs from "node:fs";
 import { MatrixClient } from "../sdk.js";
+import { validateMatrixHomeserverUrl } from "./config.js";
 import { ensureMatrixSdkLoggingConfigured } from "./logging.js";
 import {
   maybeMigrateLegacyStorage,
@@ -21,11 +22,12 @@ export async function createMatrixClient(params: {
 }): Promise<MatrixClient> {
   ensureMatrixSdkLoggingConfigured();
   const env = process.env;
+  const homeserver = validateMatrixHomeserverUrl(params.homeserver);
   const userId = params.userId?.trim() || "unknown";
   const matrixClientUserId = params.userId?.trim() || undefined;
 
   const storagePaths = resolveMatrixStoragePaths({
-    homeserver: params.homeserver,
+    homeserver,
     userId,
     accessToken: params.accessToken,
     accountId: params.accountId,
@@ -39,14 +41,14 @@ export async function createMatrixClient(params: {
 
   writeStorageMeta({
     storagePaths,
-    homeserver: params.homeserver,
+    homeserver,
     userId,
     accountId: params.accountId,
   });
 
   const cryptoDatabasePrefix = `openclaw-matrix-${storagePaths.accountKey}-${storagePaths.tokenHash}`;
 
-  return new MatrixClient(params.homeserver, params.accessToken, undefined, undefined, {
+  return new MatrixClient(homeserver, params.accessToken, undefined, undefined, {
     userId: matrixClientUserId,
     password: params.password,
     deviceId: params.deviceId,
diff --git a/extensions/matrix/src/matrix/probe.test.ts b/extensions/matrix/src/matrix/probe.test.ts
index 2bbf2534565..3d0221e0709 100644
--- a/extensions/matrix/src/matrix/probe.test.ts
+++ b/extensions/matrix/src/matrix/probe.test.ts
@@ -68,4 +68,19 @@ describe("probeMatrix", () => {
       accountId: "ops",
     });
   });
+
+  it("returns client validation errors for insecure public http homeservers", async () => {
+    createMatrixClientMock.mockRejectedValue(
+      new Error("Matrix homeserver must use https:// unless it targets a private or loopback host"),
+    );
+
+    const result = await probeMatrix({
+      homeserver: "http://matrix.example.org",
+      accessToken: "tok",
+      timeoutMs: 500,
+    });
+
+    expect(result.ok).toBe(false);
+    expect(result.error).toContain("Matrix homeserver must use https://");
+  });
 });
diff --git a/extensions/matrix/src/onboarding.ts b/extensions/matrix/src/onboarding.ts
index 123594f5e38..115a920d743 100644
--- a/extensions/matrix/src/onboarding.ts
+++ b/extensions/matrix/src/onboarding.ts
@@ -23,6 +23,7 @@ import {
   getMatrixScopedEnvVarNames,
   hasReadyMatrixEnvAuth,
   resolveScopedMatrixEnvConfig,
+  validateMatrixHomeserverUrl,
 } from "./matrix/client.js";
 import {
   resolveMatrixConfigFieldPath,
@@ -312,14 +313,12 @@ async function runMatrixConfigure(params: {
       message: "Matrix homeserver URL",
       initialValue: existing.homeserver ?? envHomeserver,
       validate: (value) => {
-        const raw = String(value ?? "").trim();
-        if (!raw) {
-          return "Required";
+        try {
+          validateMatrixHomeserverUrl(String(value ?? ""));
+          return undefined;
+        } catch (error) {
+          return error instanceof Error ? error.message : "Invalid Matrix homeserver URL";
         }
-        if (!/^https?:\/\//i.test(raw)) {
-          return "Use a full URL (https://...)";
-        }
-        return undefined;
       },
     }),
   ).trim();
diff --git a/src/plugin-sdk/matrix.ts b/src/plugin-sdk/matrix.ts
index 54b54f97823..f64749e638b 100644
--- a/src/plugin-sdk/matrix.ts
+++ b/src/plugin-sdk/matrix.ts
@@ -123,6 +123,7 @@ export {
   resolveMatrixMigrationSnapshotOutputDir,
 } from "../infra/matrix-migration-snapshot.js";
 export { fetchWithSsrFGuard } from "../infra/net/fetch-guard.js";
+export { isPrivateOrLoopbackHost } from "../gateway/net.js";
 export {
   getSessionBindingService,
   registerSessionBindingAdapter,
@@ -142,6 +143,7 @@ export { normalizePollInput } from "../polls.js";
 export {
   DEFAULT_ACCOUNT_ID,
   normalizeAccountId,
+  normalizeOptionalAccountId,
   resolveAgentIdFromSessionKey,
 } from "../routing/session-key.js";
 export type { RuntimeEnv } from "../runtime.js";