diff --git a/spec/unit/oidc/authorize.spec.ts b/spec/unit/oidc/authorize.spec.ts
index 515b9a559..087cb1289 100644
--- a/spec/unit/oidc/authorize.spec.ts
+++ b/spec/unit/oidc/authorize.spec.ts
@@ -175,6 +175,23 @@ describe("oidc authorization", () => {
 
             expect(authUrl.searchParams.get("login_hint")).toEqual("login1234");
         });
+
+        it("should generate url with response_mode=fragment", async () => {
+            const nonce = "abc123";
+
+            const authUrl = new URL(
+                await generateOidcAuthorizationUrl({
+                    metadata: delegatedAuthConfig,
+                    homeserverUrl: baseUrl,
+                    clientId,
+                    redirectUri: baseUrl,
+                    nonce,
+                    responseMode: "fragment",
+                }),
+            );
+
+            expect(authUrl.searchParams.get("response_mode")).toEqual("fragment");
+        });
     });
 
     describe("completeAuthorizationCodeGrant", () => {
diff --git a/src/oidc/authorize.ts b/src/oidc/authorize.ts
index a250b061b..a7ad00016 100644
--- a/src/oidc/authorize.ts
+++ b/src/oidc/authorize.ts
@@ -14,7 +14,15 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import { type IdTokenClaims, Log, OidcClient, SigninResponse, SigninState, WebStorageStateStore } from "oidc-client-ts";
+import {
+    type IdTokenClaims,
+    Log,
+    OidcClient,
+    type SigninRequestCreateArgs,
+    SigninResponse,
+    SigninState,
+    WebStorageStateStore,
+} from "oidc-client-ts";
 
 import { logger } from "../logger.ts";
 import { secureRandomString } from "../randomstring.ts";
@@ -127,6 +135,8 @@ export const generateAuthorizationUrl = async (
  * @param urlState - value to append to the opaque state identifier to uniquely identify the callback
  * @param loginHint - value to send as the `login_hint` to the OP, giving a hint about the login identifier the user might use to log in.
  *          See {@link https://openid.net/specs/openid-connect-core-1_0.html#AuthRequest OIDC core 3.1.2.1}.
+ * @param responseMode - value to send as the `response_mode` to the OP, selecting how auth is passed back during redirect.
+ *          See {@link https://openid.net/specs/openid-connect-core-1_0.html#AuthRequest OIDC core 3.1.2.1}.
  * @returns a Promise with the url as a string
  */
 export const generateOidcAuthorizationUrl = async ({
@@ -139,6 +149,7 @@ export const generateOidcAuthorizationUrl = async ({
     prompt,
     urlState,
     loginHint,
+    responseMode = "query",
 }: {
     clientId: string;
     metadata: ValidatedAuthMetadata;
@@ -149,6 +160,7 @@ export const generateOidcAuthorizationUrl = async ({
     prompt?: string;
     urlState?: string;
     loginHint?: string;
+    responseMode?: SigninRequestCreateArgs["response_mode"];
 }): Promise<string> => {
     const scope = generateScope();
     const oidcClient = new OidcClient({
@@ -156,7 +168,7 @@ export const generateOidcAuthorizationUrl = async ({
         client_id: clientId,
         redirect_uri: redirectUri,
         authority: metadata.issuer,
-        response_mode: "query",
+        response_mode: responseMode,
         response_type: "code",
         scope,
         stateStore: new WebStorageStateStore({ prefix: "mx_oidc_", store: window.sessionStorage }),