Abstract: This paper investigates the trajectory tracking control problem for a six-degree-of-freedom remotely operated underwater vehicle (ROV). A finite-time disturbance observer is proposed. The uncertainties in the ROV’s dynamic model, along with external disturbances, are treated as lumped disturbances. The observer effectively estimates these lumped disturbances and compensates for them in the motion system, thereby enhancing the robustness of the control system. Additionally, to address the issues of slow convergence speed and chattering during desired trajectory tracking, a super-twisting sliding mode control algorithm based on finite-time theory is designed. By developing an appropriate control law for this control system, the convergence time of tracking errors is significantly reduced, and chattering is eliminated. This improves the performance and accuracy of the control system, ensuring that the ROV can achieve trajectory tracking for various desired trajectories within a finite time.