The prescribed-time control for group consensus problems of multiagent systems (MASs) are investigated in this paper. The prescribed-time control protocols including an arbitrary non-zero group projective parameter are presented to achieve group consensus within a predetermined time of physical allowance, which is independent of system parameters and initial values. Based on algebraic graph theory, Lyapunov stability and matrix theory, sufficient conditions of the designed parameters are established to realize prescribed time group consensus under both undirected and directed topology networks. The effectiveness of the proposed approaches is verified by simulation of the unicycle nonholonomic robots system.