This paper deals with a novel control architecture for roll stabilization of an underactuated underwater vehicle. This method relies on the use of an internal rotor to generate inertial counter torque in order to cancel out the disturbances affecting the roll (unactuated coordinate). Moreover, the dynamic model incorporates the thrusters’ dynamics, and undesirable effects are compensated by a feedforward controller. The performance and efficiency of the proposed control scheme are illustrated through simulation results.