A momentum-based balance controller controls a humanoid robot to maintain balance. The balance controller derives desired rates of change of linear and angular momentum from desired motion of the robot. The balance controller then determines desired center of pressure (CoP) and desired ground reaction force (GRF) to achieve the desired rates of change of linear and angular momentum. The balance controller determines admissible CoP, GRF, and rates of change of linear and angular momentum that are optimally close to the desired value while still allowing the robot to maintain balance. The balance controller controls the robot to maintain balance based on a human motion model such that the robot's motions are human-like. Beneficially, the robot can maintain balance even when subjected to external perturbations, or when it encounters non-level and/or non-stationary ground.