This brief focuses on the problem of fixed-time adaptive trajectory tracking control for a quadrotor unmanned aerial vehicle (QUAV) subject to error constraints. By virtue of the fixed-time command filter, the phenomenon of “explosion of complexity” (EOC) existing in the conventional backstepping method is successfully eliminated, meanwhile the effect of filtered error is skillfully removed via a new fractional power error compensation mechanism. By combining the prescribed performance control and backstepping design method together with command filter technique, a fixed-time adaptive control strategy is established. It is proved that all signals of the closed-loop system are fixed-time bounded, and the position and attitude tracking errors of the QUAV approach to an arbitrarily small region of the original point within the predefined performance bounds in a fixed time. Finally, simulation results are given to show the availability of the presented fixed-time control algorithm.