diff --git a/package.json b/package.json
index d1a8985256b..b3ac2263a0c 100644
--- a/package.json
+++ b/package.json
@@ -132,7 +132,7 @@
         "matrix-encrypt-attachment": "^1.0.3",
         "matrix-events-sdk": "0.0.1",
         "matrix-js-sdk": "github:matrix-org/matrix-js-sdk#develop",
-        "matrix-widget-api": "^1.10.0",
+        "matrix-widget-api": "^1.15.0",
         "memoize-one": "^6.0.0",
         "mime": "^4.0.4",
         "oidc-client-ts": "^3.0.1",
diff --git a/src/stores/widgets/StopGapWidget.ts b/src/stores/widgets/StopGapWidget.ts
index c8de3bf0f13..d43fd140fc8 100644
--- a/src/stores/widgets/StopGapWidget.ts
+++ b/src/stores/widgets/StopGapWidget.ts
@@ -522,10 +522,8 @@ export class StopGapWidget extends EventEmitter {
         });
     };
 
-    private onToDeviceMessage = async (payload: ReceivedToDeviceMessage): Promise<void> => {
-        const { message, encryptionInfo } = payload;
-        // TODO: Update the widget API to use a proper IToDeviceMessage instead of a IRoomEvent
-        await this.messaging?.feedToDevice(message as IRoomEvent, encryptionInfo != null);
+    private onToDeviceMessage = async ({ message, encryptionInfo }: ReceivedToDeviceMessage): Promise<void> => {
+        await this.messaging?.feedToDevice(message, encryptionInfo != null);
     };
 
     /**
diff --git a/src/stores/widgets/StopGapWidgetDriver.ts b/src/stores/widgets/StopGapWidgetDriver.ts
index afd0a85cfc5..a4263d716ff 100644
--- a/src/stores/widgets/StopGapWidgetDriver.ts
+++ b/src/stores/widgets/StopGapWidgetDriver.ts
@@ -122,6 +122,7 @@ export class StopGapWidgetDriver extends WidgetDriver {
             this.allowedCapabilities.add(`org.matrix.msc2762.timeline:${inRoomId}`);
             this.allowedCapabilities.add(MatrixCapabilities.MSC4157SendDelayedEvent);
             this.allowedCapabilities.add(MatrixCapabilities.MSC4157UpdateDelayedEvent);
+            this.allowedCapabilities.add(MatrixCapabilities.MSC4354SendStickyEvent);
 
             this.allowedCapabilities.add(
                 WidgetEventCapability.forStateEvent(EventDirection.Receive, EventType.RoomName).raw,
@@ -345,6 +346,31 @@ export class StopGapWidgetDriver extends WidgetDriver {
         return { roomId, eventId: r.event_id };
     }
 
+    /**
+     * @experimental Part of MSC4354
+     * @see {@link WidgetDriver#sendStickyEvent}
+     */
+    public async sendStickyEvent(
+        stickyDurationMs: number,
+        eventType: string,
+        content: unknown,
+        targetRoomId?: string | null,
+    ): Promise<ISendEventDetails> {
+        const client = MatrixClientPeg.get();
+        const roomId = targetRoomId || SdkContextClass.instance.roomViewStore.getRoomId();
+
+        if (!client || !roomId) throw new Error("Not in a room or not attached to a client");
+
+        const r = await client._unstable_sendStickyEvent(
+            roomId,
+            stickyDurationMs,
+            null,
+            eventType as keyof TimelineEvents,
+            content as TimelineEvents[keyof TimelineEvents] & { msc4354_sticky_key: string },
+        );
+        return { roomId, eventId: r.event_id };
+    }
+
     /**
      * @experimental Part of MSC4140 & MSC4157
      * @see {@link WidgetDriver#sendDelayedEvent}
@@ -422,6 +448,48 @@ export class StopGapWidgetDriver extends WidgetDriver {
         };
     }
 
+    /**
+     * @experimental Part of MSC4354
+     * @see {@link WidgetDriver#sendStickyEvent}
+     */
+    public async sendDelayedStickyEvent(
+        delay: number | null,
+        parentDelayId: string | null,
+        stickyDurationMs: number,
+        eventType: string,
+        content: unknown,
+        targetRoomId?: string | null,
+    ): Promise<ISendDelayedEventDetails> {
+        const client = MatrixClientPeg.get();
+        const roomId = targetRoomId || SdkContextClass.instance.roomViewStore.getRoomId();
+
+        if (!client || !roomId) throw new Error("Not in a room or not attached to a client");
+
+        let delayOpts;
+        if (delay !== null) {
+            delayOpts = {
+                delay,
+                ...(parentDelayId !== null && { parent_delay_id: parentDelayId }),
+            };
+        } else if (parentDelayId !== null) {
+            delayOpts = {
+                parent_delay_id: parentDelayId,
+            };
+        } else {
+            throw new Error("Must provide at least one of delay or parentDelayId");
+        }
+
+        const r = await client._unstable_sendStickyDelayedEvent(
+            roomId,
+            stickyDurationMs,
+            delayOpts,
+            null,
+            eventType as keyof TimelineEvents,
+            content as TimelineEvents[keyof TimelineEvents] & { msc4354_sticky_key: string },
+        );
+        return { roomId, delayId: r.delay_id };
+    }
+
     /**
      * @experimental Part of MSC4140 & MSC4157
      */
diff --git a/yarn.lock b/yarn.lock
index 09f10b19e6a..776cdf75127 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -4218,7 +4218,7 @@
     classnames "^2.5.1"
     vaul "^1.0.0"
 
-"@vector-im/matrix-wysiwyg-wasm@link:../../Library/Caches/Yarn/v6/npm-@vector-im-matrix-wysiwyg-2.40.0-53c9ca5ea907d91e4515da64f20a82e5586b882c-integrity/node_modules/bindings/wysiwyg-wasm":
+"@vector-im/matrix-wysiwyg-wasm@link:../../../.cache/yarn/v6/npm-@vector-im-matrix-wysiwyg-2.40.0-53c9ca5ea907d91e4515da64f20a82e5586b882c-integrity/node_modules/bindings/wysiwyg-wasm":
   version "0.0.0"
 
 "@vector-im/matrix-wysiwyg@2.40.0":
@@ -9695,6 +9695,14 @@ matrix-widget-api@^1.10.0:
     "@types/events" "^3.0.0"
     events "^3.2.0"
 
+matrix-widget-api@^1.15.0:
+  version "1.15.0"
+  resolved "https://registry.yarnpkg.com/matrix-widget-api/-/matrix-widget-api-1.15.0.tgz#a508f72a5993a95382bdf890bd9e54525295b321"
+  integrity sha512-Yu9rX9wyF3A1sqviKgiYHz8aGgL3HhJe9OXKi/lccr1eZnNb6y+ELdbshTjs+VLKM4rkTWt6CE3THsw3f/CZhg==
+  dependencies:
+    "@types/events" "^3.0.0"
+    events "^3.2.0"
+
 mdn-data@2.0.28:
   version "2.0.28"
   resolved "https://registry.yarnpkg.com/mdn-data/-/mdn-data-2.0.28.tgz#5ec48e7bef120654539069e1ae4ddc81ca490eba"