<p>This paper addresses a composite control strategy based on a prescribed-time integral sliding mode surface and a prescribed-time disturbance observer for the trajectory tracking control of a manipulator with modeling uncertainties and external disturbances. Firstly, an innovative integral-type sliding mode surface with a time-regulation mechanism is designed. By incorporating an exponential gain function and a normalization term, the proposed surface ensures rapid convergence of the system states within a prescribed time. Secondly, an improved disturbance observer employing an exponential adaptive gain mechanism is constructed, which can accurately reconstruct composite disturbances within a prescribed-time threshold. This observer effectively estimates system uncertainties and external disturbances, guaranteeing that the observer errors converge within a prescribed time. Finally, the prescribed-time stability of the closed-loop system is rigorously proven on the basis of the Lyapunov stability theory. Simulation results demonstrate that the proposed method achieves precise trajectory tracking under varying initial conditions and prescribed-time constraints.</p>