diff --git a/src/libs/actions/OnyxUpdates.js b/src/libs/actions/OnyxUpdates.ts
similarity index 62%
rename from src/libs/actions/OnyxUpdates.js
rename to src/libs/actions/OnyxUpdates.ts
index 8e45e7dd2e66..50a4fdffc3ae 100644
--- a/src/libs/actions/OnyxUpdates.js
+++ b/src/libs/actions/OnyxUpdates.ts
@@ -1,28 +1,25 @@
-import Onyx from 'react-native-onyx';
-import _ from 'underscore';
+import Onyx, {OnyxEntry} from 'react-native-onyx';
+import {Merge} from 'type-fest';
 import PusherUtils from '../PusherUtils';
 import ONYXKEYS from '../../ONYXKEYS';
 import * as QueuedOnyxUpdates from './QueuedOnyxUpdates';
 import CONST from '../../CONST';
+import {OnyxUpdatesFromServer, OnyxUpdateEvent, Request} from '../../types/onyx';
+import Response from '../../types/onyx/Response';
 
 // This key needs to be separate from ONYXKEYS.ONYX_UPDATES_FROM_SERVER so that it can be updated without triggering the callback when the server IDs are updated. If that
 // callback were triggered it would lead to duplicate processing of server updates.
-let lastUpdateIDAppliedToClient = 0;
+let lastUpdateIDAppliedToClient: OnyxEntry<number> = 0;
 Onyx.connect({
     key: ONYXKEYS.ONYX_UPDATES_LAST_UPDATE_ID_APPLIED_TO_CLIENT,
     callback: (val) => (lastUpdateIDAppliedToClient = val),
 });
 
-/**
- * @param {Object} request
- * @param {Object} response
- * @returns {Promise}
- */
-function applyHTTPSOnyxUpdates(request, response) {
+function applyHTTPSOnyxUpdates(request: Request, response: Response) {
     console.debug('[OnyxUpdateManager] Applying https update');
     // For most requests we can immediately update Onyx. For write requests we queue the updates and apply them after the sequential queue has flushed to prevent a replay effect in
     // the UI. See https://github.com/Expensify/App/issues/12775 for more info.
-    const updateHandler = request.data.apiRequestType === CONST.API_REQUEST_TYPE.WRITE ? QueuedOnyxUpdates.queueOnyxUpdates : Onyx.update;
+    const updateHandler = request?.data?.apiRequestType === CONST.API_REQUEST_TYPE.WRITE ? QueuedOnyxUpdates.queueOnyxUpdates : Onyx.update;
 
     // First apply any onyx data updates that are being sent back from the API. We wait for this to complete and then
     // apply successData or failureData. This ensures that we do not update any pending, loading, or other UI states contained
@@ -46,55 +43,45 @@ function applyHTTPSOnyxUpdates(request, response) {
         });
 }
 
-/**
- * @param {Array} updates
- * @returns {Promise}
- */
-function applyPusherOnyxUpdates(updates) {
+function applyPusherOnyxUpdates(updates: OnyxUpdateEvent[]) {
     console.debug('[OnyxUpdateManager] Applying pusher update');
-    const pusherEventPromises = _.map(updates, (update) => PusherUtils.triggerMultiEventHandler(update.eventType, update.data));
+    const pusherEventPromises = updates.map((update) => PusherUtils.triggerMultiEventHandler(update.eventType, update.data));
     return Promise.all(pusherEventPromises).then(() => {
         console.debug('[OnyxUpdateManager] Done applying Pusher update');
     });
 }
 
 /**
- * @param {Object[]} updateParams
- * @param {String} updateParams.type
- * @param {Number} updateParams.lastUpdateID
- * @param {Object} [updateParams.request] Exists if updateParams.type === 'https'
- * @param {Object} [updateParams.response] Exists if updateParams.type === 'https'
- * @param {Object} [updateParams.updates] Exists if updateParams.type === 'pusher'
- * @returns {Promise}
+ * @param [updateParams.request] Exists if updateParams.type === 'https'
+ * @param [updateParams.response] Exists if updateParams.type === 'https'
+ * @param [updateParams.updates] Exists if updateParams.type === 'pusher'
  */
-function apply({lastUpdateID, type, request, response, updates}) {
+function apply({lastUpdateID, type, request, response, updates}: Merge<OnyxUpdatesFromServer, {updates: OnyxUpdateEvent[]; type: 'pusher'}>): Promise<void>;
+function apply({lastUpdateID, type, request, response, updates}: Merge<OnyxUpdatesFromServer, {request: Request; response: Response; type: 'https'}>): Promise<Response>;
+function apply({lastUpdateID, type, request, response, updates}: OnyxUpdatesFromServer): Promise<void | Response> | undefined {
     console.debug(`[OnyxUpdateManager] Applying update type: ${type} with lastUpdateID: ${lastUpdateID}`, {request, response, updates});
 
-    if (lastUpdateID && lastUpdateID < lastUpdateIDAppliedToClient) {
+    if (lastUpdateID && lastUpdateIDAppliedToClient && Number(lastUpdateID) < lastUpdateIDAppliedToClient) {
         console.debug('[OnyxUpdateManager] Update received was older than current state, returning without applying the updates');
         return Promise.resolve();
     }
-    if (lastUpdateID && lastUpdateID > lastUpdateIDAppliedToClient) {
-        Onyx.merge(ONYXKEYS.ONYX_UPDATES_LAST_UPDATE_ID_APPLIED_TO_CLIENT, lastUpdateID);
+    if (lastUpdateID && lastUpdateIDAppliedToClient && Number(lastUpdateID) > lastUpdateIDAppliedToClient) {
+        Onyx.merge(ONYXKEYS.ONYX_UPDATES_LAST_UPDATE_ID_APPLIED_TO_CLIENT, Number(lastUpdateID));
     }
-    if (type === CONST.ONYX_UPDATE_TYPES.HTTPS) {
+    if (type === CONST.ONYX_UPDATE_TYPES.HTTPS && request && response) {
         return applyHTTPSOnyxUpdates(request, response);
     }
-    if (type === CONST.ONYX_UPDATE_TYPES.PUSHER) {
+    if (type === CONST.ONYX_UPDATE_TYPES.PUSHER && updates) {
         return applyPusherOnyxUpdates(updates);
     }
 }
 
 /**
- * @param {Object[]} updateParams
- * @param {String} updateParams.type
- * @param {Object} [updateParams.request] Exists if updateParams.type === 'https'
- * @param {Object} [updateParams.response] Exists if updateParams.type === 'https'
- * @param {Object} [updateParams.updates] Exists if updateParams.type === 'pusher'
- * @param {Number} [updateParams.lastUpdateID]
- * @param {Number} [updateParams.previousUpdateID]
+ * @param [updateParams.request] Exists if updateParams.type === 'https'
+ * @param [updateParams.response] Exists if updateParams.type === 'https'
+ * @param [updateParams.updates] Exists if updateParams.type === 'pusher'
  */
-function saveUpdateInformation(updateParams) {
+function saveUpdateInformation(updateParams: OnyxUpdatesFromServer) {
     // Always use set() here so that the updateParams are never merged and always unique to the request that came in
     Onyx.set(ONYXKEYS.ONYX_UPDATES_FROM_SERVER, updateParams);
 }
@@ -102,10 +89,9 @@ function saveUpdateInformation(updateParams) {
 /**
  * This function will receive the previousUpdateID from any request/pusher update that has it, compare to our current app state
  * and return if an update is needed
- * @param {Number} previousUpdateID The previousUpdateID contained in the response object
- * @returns {Boolean}
+ * @param previousUpdateID The previousUpdateID contained in the response object
  */
-function doesClientNeedToBeUpdated(previousUpdateID = 0) {
+function doesClientNeedToBeUpdated(previousUpdateID = 0): boolean {
     // If no previousUpdateID is sent, this is not a WRITE request so we don't need to update our current state
     if (!previousUpdateID) {
         return false;
diff --git a/src/types/onyx/OnyxUpdatesFromServer.ts b/src/types/onyx/OnyxUpdatesFromServer.ts
index 02a96d4ce230..50b1503b90bd 100644
--- a/src/types/onyx/OnyxUpdatesFromServer.ts
+++ b/src/types/onyx/OnyxUpdatesFromServer.ts
@@ -2,13 +2,18 @@ import {OnyxUpdate} from 'react-native-onyx';
 import Request from './Request';
 import Response from './Response';
 
+type OnyxUpdateEvent = {
+    eventType: string;
+    data: OnyxUpdate[];
+};
+
 type OnyxUpdatesFromServer = {
     type: 'https' | 'pusher';
     lastUpdateID: number | string;
     previousUpdateID: number | string;
     request?: Request;
     response?: Response;
-    updates?: OnyxUpdate[];
+    updates?: OnyxUpdateEvent[];
 };
 
-export default OnyxUpdatesFromServer;
+export type {OnyxUpdatesFromServer, OnyxUpdateEvent};
diff --git a/src/types/onyx/index.ts b/src/types/onyx/index.ts
index d908c0b36ce1..47262a14540e 100644
--- a/src/types/onyx/index.ts
+++ b/src/types/onyx/index.ts
@@ -33,7 +33,7 @@ import ReimbursementAccountDraft from './ReimbursementAccountDraft';
 import WalletTransfer from './WalletTransfer';
 import ReceiptModal from './ReceiptModal';
 import MapboxAccessToken from './MapboxAccessToken';
-import OnyxUpdatesFromServer from './OnyxUpdatesFromServer';
+import {OnyxUpdatesFromServer, OnyxUpdateEvent} from './OnyxUpdatesFromServer';
 import Download from './Download';
 import PolicyMember from './PolicyMember';
 import Policy from './Policy';
@@ -93,6 +93,7 @@ export type {
     Form,
     AddDebitCardForm,
     OnyxUpdatesFromServer,
+    OnyxUpdateEvent,
     RecentWaypoints,
     RecentlyUsedCategories,
 };