Compared with one single unmanned surface vessel (USV), the multiple USVs have the advantages of strong maneuverability, high reliability, and low cost. Nowadays, the multiple USVs have the great potential applications in oceanic transportation, resource exploration, and maritime rescue. Actually, the cooperative formation control is a significant yet challenging technology for multiple USVs. This paper proposes a fixed-time adaptive distributed control strategy for the problem of cooperative formation control of multiple USVs. First, considering that only a portion of follower USVs can directly access the state information from the virtual leader, a fixed-time distributed observer is constructed for each follower USV to estimate the virtual leader’s position and velocity in fixed time. Then, based on the estimated information, a fixed-time local controller is designed for each follower USV to track the desired trajectory in fixed time by utilizing the backstepping method. Specifically, during the local controller design procedure, the parameter adaptive mechanism is adopted to compensate the model uncertainties and external perturbations. In this way, the proposed controller is smooth that the control accuracy can be guaranteed and the chattering phenomenon can be avoided simultaneously. Stability analysis shows that the proposed controller can ensure the position and velocity tracking errors of each follower USV can converge to the small neighborhoods around zero in fixed time. Finally, the effectiveness and superiority of the proposed control strategy are verified through comparative simulations.