diff --git a/lib/actions/user-actions.js b/lib/actions/user-actions.js
--- a/lib/actions/user-actions.js
+++ b/lib/actions/user-actions.js
@@ -21,7 +21,11 @@
   UpdateUserAvatarResponse,
 } from '../types/avatar-types.js';
 import type { RawEntryInfo, CalendarQuery } from '../types/entry-types.js';
-import type { IdentityServiceClient } from '../types/identity-service-types';
+import type {
+  UserLoginResponse,
+  IdentityServiceClient,
+  IdentityServiceNativeClient,
+} from '../types/identity-service-types';
 import type {
   RawMessageInfo,
   MessageTruncationStatuses,
@@ -220,6 +224,56 @@
     };
   };
 
+const identityRegisterActionTypes = Object.freeze({
+  started: 'IDENTITY_REGISTER_STARTED',
+  success: 'IDENTITY_REGISTER_SUCCESS',
+  failed: 'IDENTITY_REGISTER_FAILED',
+});
+function useIdentityRegister(
+  client: IdentityServiceNativeClient,
+  username: string,
+  password: string,
+  keyPayload: string,
+  keyPayloadSignature: string,
+  contentPrekey: string,
+  contentPrekeySignature: string,
+  notifPrekey: string,
+  notifPrekeySignature: string,
+  contentOneTimeKeys: $ReadOnlyArray<string>,
+  notifOneTimeKeys: $ReadOnlyArray<string>,
+): () => Promise<UserLoginResponse> {
+  const identityRegister = React.useCallback(async () => {
+    const registrationResult = await client.registerUser(
+      username,
+      password,
+      keyPayload,
+      keyPayloadSignature,
+      contentPrekey,
+      contentPrekeySignature,
+      notifPrekey,
+      notifPrekeySignature,
+      contentOneTimeKeys,
+      notifOneTimeKeys,
+    );
+    const { userID, accessToken } = JSON.parse(registrationResult);
+    return { accessToken, userId: userID };
+  }, [
+    client,
+    contentOneTimeKeys,
+    contentPrekey,
+    contentPrekeySignature,
+    keyPayload,
+    keyPayloadSignature,
+    notifOneTimeKeys,
+    notifPrekey,
+    notifPrekeySignature,
+    password,
+    username,
+  ]);
+
+  return identityRegister;
+}
+
 function mergeUserInfos(
   ...userInfoArrays: Array<$ReadOnlyArray<UserInfo>>
 ): UserInfo[] {
@@ -561,4 +615,6 @@
   setAccessTokenActionType,
   deleteIdentityAccountActionTypes,
   useDeleteIdentityAccount,
+  identityRegisterActionTypes,
+  useIdentityRegister,
 };
diff --git a/lib/types/identity-service-types.js b/lib/types/identity-service-types.js
--- a/lib/types/identity-service-types.js
+++ b/lib/types/identity-service-types.js
@@ -27,6 +27,22 @@
   ) => Promise<void>;
 }
 
+// Native-specific client methods
+export interface IdentityServiceNativeClient {
+  +registerUser: (
+    username: string,
+    password: string,
+    keyPayload: string,
+    keyPayloadSignature: string,
+    contentPrekey: string,
+    contentPrekeySignature: string,
+    notifPrekey: string,
+    notifPrekeySignature: string,
+    contentOneTimeKeys: $ReadOnlyArray<string>,
+    notifOneTimeKeys: $ReadOnlyArray<string>,
+  ) => Promise<string>;
+}
+
 export type IdentityServiceAuthLayer = {
   +userID: string,
   +deviceID: string,