This paper concerns the predefined-time bipartite consensus control for uncertain nonlinear multiagent systems under a signed directed topology. All agents have high-order uncertain nonlinear dynamic characteristics satisfying a time-varying Lipschitz growth condition, and their partial state information is not available for measurement. In this case, we put forward a novel output-feedback-based predefined-time leader-following bipartite consensus control strategy. A predefined-time compensator for each follower is firstly constructed with a time-varying gain by utilizing its relative output information. Then, a novel linear-like output feedback predefined-time distributed control protocol is developed for each follower by means of the compensator. By making two artful state transitions, the bipartite consensus problem is reduced to a stabilization one of nonlinear systems. By means of the Lyapunov stability theorem, we strictly prove that the designed controllers can ensure that all agents realize bipartite consensus in predefined time. Finally, two simulation examples are given to validate the viability of the developed theoretical algorithm.