This paper investigates the fixed-time trajectory tracking control problem for a nonholonomic mobile robot. Firstly, the tracking error system is derived for the mobile robot by the aid of a global invertible transformation. Then, based on the unified error dynamics and by using the fixed-time control method, continuous fixed-time tracking controllers are developed for the mobile robot such that the robot can track the desired trajectory in a fixed time. Moreover, the settling time is independent of the system initial conditions and only determined by the controller parameters. Finally, numerical simulations are provided to demonstrate the effectiveness of the theoretical results.