diff --git a/.changeset/registration-session-cookie.md b/.changeset/registration-session-cookie.md
new file mode 100644
index 0000000..9a5b010
--- /dev/null
+++ b/.changeset/registration-session-cookie.md
@@ -0,0 +1,13 @@
+---
+"@seamless-auth/core": minor
+"@seamless-auth/express": patch
+---
+
+Issue a session on OTP-based registration. Registration now starts with just an
+email, and verifying the registration email OTP completes sign-up and returns a
+session. The adapter previously proxied `/otp/verify-email-otp` and
+`/otp/verify-phone-otp` without setting cookies, so browser users finished
+registration unauthenticated. A new `verifyRegistrationOtpHandler` (core) plus a
+`verifyRegistrationOtp` express handler now set the session cookies on these
+routes (tolerating a phone-first step that returns no session yet), mirroring the
+login OTP verify handlers.
diff --git a/packages/core/src/handlers/verifyLoginOtpHandler.ts b/packages/core/src/handlers/verifyLoginOtpHandler.ts
index 1dc257c..7057763 100644
--- a/packages/core/src/handlers/verifyLoginOtpHandler.ts
+++ b/packages/core/src/handlers/verifyLoginOtpHandler.ts
@@ -28,15 +28,16 @@ export interface VerifyLoginOtpResult {
   }[];
 }
 
-export async function verifyLoginOtpHandler(
+// Shared by the login and registration OTP verify handlers: POST to the given
+// auth-server path and, when the response carries a session, validate the signed
+// access token and build the session cookies. Registration can complete without
+// a session yet (e.g. a phone-first step before email is verified), in which case
+// there is no token to turn into cookies — the body is returned as-is.
+async function verifyOtp(
+  path: string,
   input: VerifyLoginOtpInput,
   opts: VerifyLoginOtpOptions,
 ): Promise<VerifyLoginOtpResult> {
-  const path =
-    input.kind === "email"
-      ? "otp/verify-login-email-otp"
-      : "otp/verify-login-phone-otp";
-
   const up = await authFetch(`${opts.authServerUrl}/${path}`, {
     method: "POST",
     body: input.body,
@@ -53,6 +54,13 @@ export async function verifyLoginOtpHandler(
     };
   }
 
+  if (!data?.token) {
+    return {
+      status: up.status,
+      body: data,
+    };
+  }
+
   const verifiedAccessToken = await verifySignedAuthResponse(
     data.token,
     opts.authServerUrl,
@@ -101,3 +109,25 @@ export async function verifyLoginOtpHandler(
     ],
   };
 }
+
+export async function verifyLoginOtpHandler(
+  input: VerifyLoginOtpInput,
+  opts: VerifyLoginOtpOptions,
+): Promise<VerifyLoginOtpResult> {
+  const path =
+    input.kind === "email"
+      ? "otp/verify-login-email-otp"
+      : "otp/verify-login-phone-otp";
+
+  return verifyOtp(path, input, opts);
+}
+
+export async function verifyRegistrationOtpHandler(
+  input: VerifyLoginOtpInput,
+  opts: VerifyLoginOtpOptions,
+): Promise<VerifyLoginOtpResult> {
+  const path =
+    input.kind === "email" ? "otp/verify-email-otp" : "otp/verify-phone-otp";
+
+  return verifyOtp(path, input, opts);
+}
diff --git a/packages/express/src/createServer.ts b/packages/express/src/createServer.ts
index 62deeae..2625073 100644
--- a/packages/express/src/createServer.ts
+++ b/packages/express/src/createServer.ts
@@ -8,7 +8,10 @@ import { login } from "./handlers/login";
 import { finishLogin } from "./handlers/finishLogin";
 import { register } from "./handlers/register";
 import { requestOtp } from "./handlers/requestOtp";
-import { verifyLoginOtp } from "./handlers/verifyLoginOtp";
+import {
+  verifyLoginOtp,
+  verifyRegistrationOtp,
+} from "./handlers/verifyLoginOtp";
 import { switchOrganization } from "./handlers/switchOrganization";
 import { finishRegister } from "./handlers/finishRegister";
 import { me } from "./handlers/me";
@@ -274,13 +277,11 @@ export function createSeamlessAuthServer(
     finishRegister(req, res, resolvedOpts),
   );
 
-  r.post(
-    "/otp/verify-phone-otp",
-    proxyWithIdentity("otp/verify-phone-otp", "preAuth"),
+  r.post("/otp/verify-phone-otp", (req, res) =>
+    verifyRegistrationOtp(req, res, resolvedOpts, "phone"),
   );
-  r.post(
-    "/otp/verify-email-otp",
-    proxyWithIdentity("otp/verify-email-otp", "preAuth"),
+  r.post("/otp/verify-email-otp", (req, res) =>
+    verifyRegistrationOtp(req, res, resolvedOpts, "email"),
   );
   r.post("/otp/verify-login-phone-otp", (req, res) =>
     verifyLoginOtp(req, res, resolvedOpts, "phone"),
diff --git a/packages/express/src/handlers/verifyLoginOtp.ts b/packages/express/src/handlers/verifyLoginOtp.ts
index 19f361c..8a4a556 100644
--- a/packages/express/src/handlers/verifyLoginOtp.ts
+++ b/packages/express/src/handlers/verifyLoginOtp.ts
@@ -1,15 +1,19 @@
 import { Request, Response } from "express";
-import { verifyLoginOtpHandler } from "@seamless-auth/core/handlers/verifyLoginOtpHandler";
+import {
+  verifyLoginOtpHandler,
+  verifyRegistrationOtpHandler,
+} from "@seamless-auth/core/handlers/verifyLoginOtpHandler";
 import { setSessionCookie } from "../internal/cookie";
 import { buildServiceAuthorization } from "../internal/buildAuthorization";
 import { buildForwardedClientIp } from "../internal/buildForwardedClientIp";
 import { SeamlessAuthServerOptions } from "../createServer";
 
-export async function verifyLoginOtp(
+async function verifyOtp(
   req: Request & { cookiePayload?: any },
   res: Response,
   opts: SeamlessAuthServerOptions,
   kind: "email" | "phone",
+  flow: "login" | "register",
 ) {
   const cookieSigner = {
     secret: opts.cookieSecret,
@@ -20,7 +24,10 @@ export async function verifyLoginOtp(
         : ("lax" as "none" | "lax"),
   };
 
-  const result = await verifyLoginOtpHandler(
+  const handler =
+    flow === "register" ? verifyRegistrationOtpHandler : verifyLoginOtpHandler;
+
+  const result = await handler(
     {
       body: req.body,
       authorization: buildServiceAuthorization(req, opts),
@@ -60,3 +67,24 @@ export async function verifyLoginOtp(
 
   return res.status(result.status).json(result.body);
 }
+
+export function verifyLoginOtp(
+  req: Request & { cookiePayload?: any },
+  res: Response,
+  opts: SeamlessAuthServerOptions,
+  kind: "email" | "phone",
+) {
+  return verifyOtp(req, res, opts, kind, "login");
+}
+
+// Registration OTP verify: identical cookie handling, but a successful email
+// verify now completes registration and issues a session, so the session cookies
+// must be set here (a phone-first step that returns no session sets none).
+export function verifyRegistrationOtp(
+  req: Request & { cookiePayload?: any },
+  res: Response,
+  opts: SeamlessAuthServerOptions,
+  kind: "email" | "phone",
+) {
+  return verifyOtp(req, res, opts, kind, "register");
+}