diff --git a/backend/src/server/routes/v3/signup-router.ts b/backend/src/server/routes/v3/signup-router.ts
index 59131464a..276a2e8cb 100644
--- a/backend/src/server/routes/v3/signup-router.ts
+++ b/backend/src/server/routes/v3/signup-router.ts
@@ -179,7 +179,8 @@ export const registerSignupRouter = async (server: FastifyZodProvider) => {
         encryptedPrivateKeyIV: z.string().trim(),
         encryptedPrivateKeyTag: z.string().trim(),
         salt: z.string().trim(),
-        verifier: z.string().trim()
+        verifier: z.string().trim(),
+        metadata: z.string().optional()
       }),
       response: {
         200: z.object({
diff --git a/backend/src/services/auth-token/auth-token-types.ts b/backend/src/services/auth-token/auth-token-types.ts
index 8917bd672..dbe949fd9 100644
--- a/backend/src/services/auth-token/auth-token-types.ts
+++ b/backend/src/services/auth-token/auth-token-types.ts
@@ -49,3 +49,14 @@ export type TIssueAuthTokenDTO = {
   ip: string;
   userAgent: string;
 };
+
+export enum TokenMetadataType {
+  InviteToProjects = "projects-invite"
+}
+
+// TODO: Split the payloads into separate types for better type inference (not needed until we add more types of metadata)
+export type TTokenMetadata = {
+  type: TokenMetadataType.InviteToProjects;
+  projectIds: string[];
+  userId: string;
+};
diff --git a/backend/src/services/auth/auth-signup-service.ts b/backend/src/services/auth/auth-signup-service.ts
index 83a5b27d9..8714f5081 100644
--- a/backend/src/services/auth/auth-signup-service.ts
+++ b/backend/src/services/auth/auth-signup-service.ts
@@ -1,7 +1,7 @@
 import bcrypt from "bcrypt";
 import jwt from "jsonwebtoken";
 
-import { OrgMembershipStatus, TableName } from "@app/db/schemas";
+import { OrgMembershipStatus, ProjectMembershipRole, TableName } from "@app/db/schemas";
 import { convertPendingGroupAdditionsToGroupMemberships } from "@app/ee/services/group/group-fns";
 import { TUserGroupMembershipDALFactory } from "@app/ee/services/group/user-group-membership-dal";
 import { TLicenseServiceFactory } from "@app/ee/services/license/license-service";
@@ -9,7 +9,7 @@ import { isAuthMethodSaml } from "@app/ee/services/permission/permission-fns";
 import { getConfig } from "@app/lib/config/env";
 import { infisicalSymmetricEncypt } from "@app/lib/crypto/encryption";
 import { getUserPrivateKey } from "@app/lib/crypto/srp";
-import { BadRequestError } from "@app/lib/errors";
+import { BadRequestError, UnauthorizedError } from "@app/lib/errors";
 import { isDisposableEmail } from "@app/lib/validator";
 import { TGroupProjectDALFactory } from "@app/services/group-project/group-project-dal";
 import { TProjectDALFactory } from "@app/services/project/project-dal";
@@ -17,9 +17,12 @@ import { TProjectBotDALFactory } from "@app/services/project-bot/project-bot-dal
 import { TProjectKeyDALFactory } from "@app/services/project-key/project-key-dal";
 
 import { TAuthTokenServiceFactory } from "../auth-token/auth-token-service";
-import { TokenType } from "../auth-token/auth-token-types";
+import { TokenType, TTokenMetadata } from "../auth-token/auth-token-types";
 import { TOrgDALFactory } from "../org/org-dal";
 import { TOrgServiceFactory } from "../org/org-service";
+import { TProjectMembershipDALFactory } from "../project-membership/project-membership-dal";
+import { addMembersToProject } from "../project-membership/project-membership-fns";
+import { TProjectUserMembershipRoleDALFactory } from "../project-membership/project-user-membership-role-dal";
 import { SmtpTemplates, TSmtpService } from "../smtp/smtp-service";
 import { TUserDALFactory } from "../user/user-dal";
 import { TAuthDALFactory } from "./auth-dal";
@@ -32,10 +35,14 @@ type TAuthSignupDep = {
   userDAL: TUserDALFactory;
   userGroupMembershipDAL: Pick<
     TUserGroupMembershipDALFactory,
-    "find" | "transaction" | "insertMany" | "deletePendingUserGroupMembershipsByUserIds"
+    | "find"
+    | "transaction"
+    | "insertMany"
+    | "deletePendingUserGroupMembershipsByUserIds"
+    | "findUserGroupMembershipsInProject"
   >;
   projectKeyDAL: Pick<TProjectKeyDALFactory, "find" | "findLatestProjectKey" | "insertMany">;
-  projectDAL: Pick<TProjectDALFactory, "findProjectGhostUser">;
+  projectDAL: Pick<TProjectDALFactory, "findProjectGhostUser" | "findProjectById">;
   projectBotDAL: Pick<TProjectBotDALFactory, "findOne">;
   groupProjectDAL: Pick<TGroupProjectDALFactory, "find">;
   orgService: Pick<TOrgServiceFactory, "createOrganization">;
@@ -43,6 +50,8 @@ type TAuthSignupDep = {
   tokenService: TAuthTokenServiceFactory;
   smtpService: TSmtpService;
   licenseService: Pick<TLicenseServiceFactory, "updateSubscriptionOrgMemberCount">;
+  projectMembershipDAL: Pick<TProjectMembershipDALFactory, "find" | "transaction" | "insertMany">;
+  projectUserMembershipRoleDAL: Pick<TProjectUserMembershipRoleDALFactory, "insertMany">;
 };
 
 export type TAuthSignupFactory = ReturnType<typeof authSignupServiceFactory>;
@@ -58,6 +67,8 @@ export const authSignupServiceFactory = ({
   smtpService,
   orgService,
   orgDAL,
+  projectMembershipDAL,
+  projectUserMembershipRoleDAL,
   licenseService
 }: TAuthSignupDep) => {
   // first step of signup. create user and send email
@@ -301,7 +312,8 @@ export const authSignupServiceFactory = ({
     encryptedPrivateKey,
     encryptedPrivateKeyIV,
     encryptedPrivateKeyTag,
-    authorization
+    authorization,
+    metadata
   }: TCompleteAccountInviteDTO) => {
     const user = await userDAL.findUserByUsername(email);
     if (!user || (user && user.isAccepted)) {
@@ -358,6 +370,38 @@ export const authSignupServiceFactory = ({
         tx
       );
 
+      if (metadata) {
+        const metadataObj = jwt.verify(metadata, appCfg.AUTH_SECRET) as TTokenMetadata;
+
+        if (user.id !== metadataObj.userId) {
+          throw new UnauthorizedError({
+            message: "Malformed or invalid metadata token"
+          });
+        }
+
+        for await (const projectId of metadataObj.projectIds) {
+          await addMembersToProject({
+            orgDAL,
+            projectDAL,
+            projectMembershipDAL,
+            projectKeyDAL,
+            userGroupMembershipDAL,
+            projectBotDAL,
+            projectUserMembershipRoleDAL,
+            smtpService
+          }).addMembersToNonE2EEProject(
+            {
+              emails: [user.email!],
+              usernames: [],
+              projectId,
+              projectMembershipRole: ProjectMembershipRole.Member,
+              sendEmails: false
+            },
+            tx
+          );
+        }
+      }
+
       const updatedMembersips = await orgDAL.updateMembership(
         { inviteEmail: email, status: OrgMembershipStatus.Invited },
         { userId: us.id, status: OrgMembershipStatus.Accepted },
diff --git a/frontend/src/pages/signupinvite.tsx b/frontend/src/pages/signupinvite.tsx
index 725dc6113..9c5c01b32 100644
--- a/frontend/src/pages/signupinvite.tsx
+++ b/frontend/src/pages/signupinvite.tsx
@@ -64,6 +64,10 @@ export default function SignupInvite() {
   const email = (parsedUrl.to as string)?.replace(" ", "+").trim();
   const { config } = useServerConfig();
 
+  const queryParams = new URLSearchParams(window.location.search);
+
+  const metadata = queryParams.get("metadata") || undefined;
+
   const { mutateAsync: selectOrganization } = useSelectOrganization();
 
   useEffect(() => {
@@ -160,7 +164,8 @@ export default function SignupInvite() {
                 encryptedPrivateKeyIV,
                 encryptedPrivateKeyTag,
                 salt: result.salt,
-                verifier: result.verifier
+                verifier: result.verifier,
+                metadata
               });
 
               // unset temporary signup JWT token and set JWT token