diff --git a/server/controllers/userController/getUserById/getUserById.test.ts b/server/controllers/userController/getUserById/getUserById.test.ts
new file mode 100644
index 0000000..ee29c77
--- /dev/null
+++ b/server/controllers/userController/getUserById/getUserById.test.ts
@@ -0,0 +1,78 @@
+import app from '../../../app';
+import request, { Response } from 'supertest';
+import User from '../../../models/userModel';
+
+const invalidUserId = 'invalidUserId123';
+const nonExistentUserId = '5f8f8c44b54764421b7156c4';
+const testEmail = 'john.doe@codehammers.com';
+const testPassword = 'password123';
+
+const createUser = async () => {
+  const user = await User.create({
+    firstName: 'John',
+    lastName: 'Doe',
+    email: 'john.doe@codehammers.com',
+    password: 'password123',
+  });
+  return user;
+};
+
+const loginAndGetCookie = async () => {
+  const response = await request(app)
+    .post('/api/users/login')
+    .send({ email: testEmail, password: testPassword });
+  return response.headers['set-cookie'];
+};
+
+describe('Tests for userController.getUserById', () => {
+  const baseUrl = '/api/users';
+
+  describe('Get User By Id Failure Tests', () => {
+    let authCookie: string;
+
+    beforeEach(async () => {
+      await User.deleteMany();
+      await createUser();
+      authCookie = await loginAndGetCookie();
+    });
+
+    it('🧪 Fails if userId is invalid', async () => {
+      const response = await request(app)
+        .get(`${baseUrl}/${invalidUserId}`)
+        .set('Cookie', authCookie)
+        .send();
+
+      expect(response.status).toEqual(400);
+      expect(response.body[0].message).toEqual('Invalid user ID format');
+      expect(response.body[0].field).toEqual('user ID');
+    });
+
+    it('🧪 Fails if user is not found', async () => {
+      const response = await request(app)
+        .get(`${baseUrl}/${nonExistentUserId}`)
+        .set('Cookie', authCookie)
+        .send();
+
+      expect(response.status).toEqual(404);
+      expect(response.body[0].message).toEqual('Not Found');
+    });
+  });
+
+  describe('Get User By Id Success Tests', () => {
+    let successResponse: Response;
+    let authCookie: string;
+
+    it('🧪 Retrieves the user successfully with a 200 status', async () => {
+      await User.deleteMany();
+      const user = await createUser();
+      authCookie = await loginAndGetCookie();
+      successResponse = await request(app)
+        .get(`${baseUrl}/${user.id}`)
+        .set('Cookie', authCookie)
+        .send();
+      expect(successResponse.status).toEqual(200);
+      expect(successResponse.body._id).toEqual(user.id);
+      expect(successResponse.body.email).toEqual('john.doe@codehammers.com');
+    });
+  });
+});
diff --git a/server/controllers/userController/getUserById/getUserById.ts b/server/controllers/userController/getUserById/getUserById.ts
index 47bd5aa..640ef2d 100644
--- a/server/controllers/userController/getUserById/getUserById.ts
+++ b/server/controllers/userController/getUserById/getUserById.ts
@@ -1,28 +1,25 @@
+import mongoose from 'mongoose';
 import User from '../../../models/userModel';
-import { Request, Response, NextFunction } from 'express';
+import { Request, Response } from 'express';
+import { NotFoundError, ValidationError, RequestValidationError } from '../../../errors';
 import { UserType } from '../../../types/user';
 
 // ENDPOINT  GET api/users/:userId
 // PURPOSE   Get user by id
 // ACCESS    Private
-const getUserById = async (req: Request, res: Response, next: NextFunction) => {
+const getUserById = async (req: Request, res: Response) => {
   const { userId } = req.params;
+  if (!mongoose.Types.ObjectId.isValid(userId)) {
+    throw new RequestValidationError([new ValidationError('Invalid user ID format', 'user ID')]);
+  }
 
-  try {
-    const user: UserType | null = await User.findOne({ _id: userId });
+  const user: UserType | null = await User.findOne({ _id: userId });
 
-    if (!user) {
-      return res.status(401).json({ msg: 'User not found!' }); //TODO Move to global error handler
-    }
-    res.locals.user = user;
-    return res.status(200).json(res.locals.user);
-  } catch (error) {
-    return next({
-      log: 'Express error in getUserById Middleware',
-      status: 500,
-      message: { err: 'An error occurred during retrieval' },
-    });
+  if (!user) {
+    throw new NotFoundError();
   }
+  res.locals.user = user;
+  return res.status(200).json(res.locals.user);
 };
 
 export default getUserById;