diff --git a/src/server/session/stateful-session-store.test.ts b/src/server/session/stateful-session-store.test.ts
index ec04b4d10..add110773 100644
--- a/src/server/session/stateful-session-store.test.ts
+++ b/src/server/session/stateful-session-store.test.ts
@@ -9,7 +9,7 @@ import {
   ResponseCookies,
   sign
 } from "../cookies";
-import { LegacySessionPayload } from "./normalize-session";
+import { LEGACY_COOKIE_NAME, LegacySessionPayload } from "./normalize-session";
 import { StatefulSessionStore } from "./stateful-session-store";
 
 describe("Stateful Session Store", async () => {
@@ -645,6 +645,45 @@ describe("Stateful Session Store", async () => {
         expect(cookie?.secure).toEqual(false);
       });
     });
+
+
+    it("should remove the legacy cookie if it exists", async () => {
+      const currentTime = Date.now();
+      const createdAt = Math.floor(currentTime / 1000);
+      const secret = await generateSecret(32);
+      const session: SessionData = {
+        user: { sub: "user_123" },
+        tokenSet: {
+          accessToken: "at_123",
+          refreshToken: "rt_123",
+          expiresAt: 123456
+        },
+        internal: {
+          sid: "auth0-sid",
+          createdAt
+        }
+      };
+      const store = {
+        get: vi.fn(),
+        set: vi.fn(),
+        delete: vi.fn()
+      };
+
+      const requestCookies = new RequestCookies(new Headers());
+      const responseCookies = new ResponseCookies(new Headers());
+
+      const sessionStore = new StatefulSessionStore({
+        secret,
+        store,
+      });
+
+      vi.spyOn(requestCookies, "has").mockReturnValue(true);
+      vi.spyOn(responseCookies, "delete");
+
+      await sessionStore.set(requestCookies, responseCookies, session);
+
+      expect(responseCookies.delete).toHaveBeenCalledWith(LEGACY_COOKIE_NAME);
+    });
   });
 
   describe("delete", async () => {
diff --git a/src/server/session/stateful-session-store.ts b/src/server/session/stateful-session-store.ts
index 1fc5ae569..04206981f 100644
--- a/src/server/session/stateful-session-store.ts
+++ b/src/server/session/stateful-session-store.ts
@@ -147,6 +147,12 @@ export class StatefulSessionStore extends AbstractSessionStore {
 
     // to enable read-after-write in the same request for middleware
     reqCookies.set(this.sessionCookieName, jwe.toString());
+
+    // Any existing v3 cookie can also be deleted once we have set a v4 cookie.
+    // In stateful sessions, we do not have to worry about chunking.
+    if (reqCookies.has(LEGACY_COOKIE_NAME)) {
+      resCookies.delete(LEGACY_COOKIE_NAME);
+    }
   }
 
   async delete(
diff --git a/src/server/session/stateless-session-store.test.ts b/src/server/session/stateless-session-store.test.ts
index bc2860e0b..1983efee7 100644
--- a/src/server/session/stateless-session-store.test.ts
+++ b/src/server/session/stateless-session-store.test.ts
@@ -3,7 +3,7 @@ import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { generateSecret } from "../../test/utils";
 import { SessionData } from "../../types";
 import { decrypt, encrypt, RequestCookies, ResponseCookies } from "../cookies";
-import { LegacySession } from "./normalize-session";
+import { LEGACY_COOKIE_NAME, LegacySession } from "./normalize-session";
 import { StatelessSessionStore } from "./stateless-session-store";
 
 describe("Stateless Session Store", async () => {
@@ -313,6 +313,72 @@ describe("Stateless Session Store", async () => {
         expect(cookie?.maxAge).toEqual(0); // cookie should expire immediately
         expect(cookie?.secure).toEqual(false);
       });
+
+      it("should delete the legacy cookie if it exists", async () => {
+        const currentTime = Date.now();
+        const createdAt = Math.floor(currentTime / 1000);
+        const secret = await generateSecret(32);
+        const session: SessionData = {
+          user: { sub: "user_123" },
+          tokenSet: {
+            accessToken: "at_123",
+            refreshToken: "rt_123",
+            expiresAt: 123456
+          },
+          internal: {
+            sid: "auth0-sid",
+            createdAt
+          }
+        };
+        const requestCookies = new RequestCookies(new Headers());
+        const responseCookies = new ResponseCookies(new Headers());
+
+        const sessionStore = new StatelessSessionStore({
+          secret,
+        });
+
+        vi.spyOn(responseCookies, "delete");
+        vi.spyOn(requestCookies, "has").mockReturnValue(true);
+
+        await sessionStore.set(requestCookies, responseCookies, session);
+
+        expect(responseCookies.delete).toHaveBeenCalledWith(LEGACY_COOKIE_NAME);
+      });
+
+      it("should delete the legacy cookie chunks if they exists", async () => {
+        const currentTime = Date.now();
+        const createdAt = Math.floor(currentTime / 1000);
+        const secret = await generateSecret(32);
+        const session: SessionData = {
+          user: { sub: "user_123" },
+          tokenSet: {
+            accessToken: "at_123",
+            refreshToken: "rt_123",
+            expiresAt: 123456
+          },
+          internal: {
+            sid: "auth0-sid",
+            createdAt
+          }
+        };
+        const requestCookies = new RequestCookies(new Headers());
+        const responseCookies = new ResponseCookies(new Headers());
+
+        const sessionStore = new StatelessSessionStore({
+          secret,
+        });
+
+        vi.spyOn(responseCookies, "delete");
+        vi.spyOn(requestCookies, "getAll").mockReturnValue([
+          { name: `${LEGACY_COOKIE_NAME}__0`, value: '' },
+          { name: `${LEGACY_COOKIE_NAME}__1`, value: '' }
+        ]);
+
+        await sessionStore.set(requestCookies, responseCookies, session);
+
+        expect(responseCookies.delete).toHaveBeenCalledWith(`${LEGACY_COOKIE_NAME}__0`);
+        expect(responseCookies.delete).toHaveBeenCalledWith(`${LEGACY_COOKIE_NAME}__1`);
+      });
     });
 
     describe("with rolling sessions disabled", async () => {
diff --git a/src/server/session/stateless-session-store.ts b/src/server/session/stateless-session-store.ts
index e52da8da7..bdf628aa4 100644
--- a/src/server/session/stateless-session-store.ts
+++ b/src/server/session/stateless-session-store.ts
@@ -117,6 +117,10 @@ export class StatelessSessionStore extends AbstractSessionStore {
         )
       );
     }
+    
+    // Any existing v3 cookie can be deleted as soon as we have set a v4 cookie.
+    // In stateless sessions, we do have to ensure we delete all chunks.
+    cookies.deleteChunkedCookie(LEGACY_COOKIE_NAME, reqCookies, resCookies);
   }
 
   async delete(