diff --git a/keyserver/src/creators/account-creator.js b/keyserver/src/creators/account-creator.js
--- a/keyserver/src/creators/account-creator.js
+++ b/keyserver/src/creators/account-creator.js
@@ -9,9 +9,10 @@
 import { policyTypes } from 'lib/facts/policies.js';
 import { validUsernameRegex } from 'lib/shared/account-utils.js';
 import type {
+  UserIdentifier,
   RegisterResponse,
   RegisterRequest,
-} from 'lib/types/account-types.js';
+} from 'lib/types/account-types';
 import type {
   ReservedUsernameMessage,
   SignedIdentityKeysBlob,
@@ -296,6 +297,95 @@
   return id;
 }
 
+export type ProcessOLMAccountCreationRequest = {
+  +userID: string,
+  +identifier: UserIdentifier,
+  +calendarQuery: CalendarQuery,
+  +deviceTokenUpdateRequest?: ?DeviceTokenUpdateRequest,
+  +platformDetails: PlatformDetails,
+  +signedIdentityKeysBlob: SignedIdentityKeysBlob,
+};
+// Note: `processOLMAccountCreation(...)` assumes that the validity of
+//       `ProcessOLMAccountCreationRequest` was checked at call site.
+async function processOLMAccountCreation(
+  viewer: Viewer,
+  request: ProcessOLMAccountCreationRequest,
+): Promise<void> {
+  const { calendarQuery, signedIdentityKeysBlob } = request;
+  await verifyCalendarQueryThreadIDs(calendarQuery);
+
+  const time = Date.now();
+  const deviceToken = request.deviceTokenUpdateRequest
+    ? request.deviceTokenUpdateRequest.deviceToken
+    : viewer.deviceToken;
+  const newUserRow = [
+    request.userID,
+    request.identifier.username,
+    request.identifier.walletAddress,
+    time,
+  ];
+  const newUserQuery = SQL`
+    INSERT INTO users(id, username, ethereum_address, creation_time)
+    VALUES ${[newUserRow]}
+  `;
+  const [userViewerData] = await Promise.all([
+    createNewUserCookie(request.userID, {
+      platformDetails: request.platformDetails,
+      deviceToken,
+      signedIdentityKeysBlob,
+    }),
+    deleteCookie(viewer.cookieID),
+    dbQuery(newUserQuery),
+  ]);
+  viewer.setNewCookie(userViewerData);
+
+  await setNewSession(viewer, calendarQuery, 0);
+
+  await Promise.all([
+    updateThread(
+      createScriptViewer(ashoat.id),
+      {
+        threadID: genesis.id,
+        changes: { newMemberIDs: [request.userID] },
+      },
+      { forceAddMembers: true, silenceMessages: true, ignorePermissions: true },
+    ),
+    viewerAcknowledgmentUpdater(viewer, policyTypes.tosAndPrivacyPolicy),
+  ]);
+
+  const [privateThreadResult, ashoatThreadResult] = await Promise.all([
+    createPrivateThread(viewer),
+    createThread(
+      viewer,
+      {
+        type: threadTypes.PERSONAL,
+        initialMemberIDs: [ashoat.id],
+      },
+      { forceAddMembers: true },
+    ),
+  ]);
+  const ashoatThreadID = ashoatThreadResult.newThreadID;
+  const privateThreadID = privateThreadResult.newThreadID;
+
+  let messageTime = Date.now();
+  const ashoatMessageDatas = ashoatMessages.map(message => ({
+    type: messageTypes.TEXT,
+    threadID: ashoatThreadID,
+    creatorID: ashoat.id,
+    time: messageTime++,
+    text: message,
+  }));
+  const privateMessageDatas = privateMessages.map(message => ({
+    type: messageTypes.TEXT,
+    threadID: privateThreadID,
+    creatorID: commbot.userID,
+    time: messageTime++,
+    text: message,
+  }));
+  const messageDatas = [...ashoatMessageDatas, ...privateMessageDatas];
+  await Promise.all([createMessages(viewer, messageDatas)]);
+}
+
 async function createAndSendReservedUsernameMessage(
   payload: $ReadOnlyArray<string>,
 ) {
@@ -316,4 +406,4 @@
   await rustAPI.addReservedUsernames(stringifiedMessage, signature);
 }
 
-export { createAccount, processSIWEAccountCreation };
+export { createAccount, processSIWEAccountCreation, processOLMAccountCreation };
diff --git a/lib/types/account-types.js b/lib/types/account-types.js
--- a/lib/types/account-types.js
+++ b/lib/types/account-types.js
@@ -172,6 +172,11 @@
   +notAcknowledgedPolicies?: $ReadOnlyArray<PolicyType>,
 };
 
+export type UserIdentifier = {
+  +username: string,
+  +walletAddress?: ?string,
+};
+
 type KeyserverRequestData = {
   +initialContentEncryptedMessage: string,
   +initialNotificationsEncryptedMessage: string,