In this paper, a novel online motion planning method for double-pendulum overhead cranes is proposed. The proposed trajectory is made up of two parts: anti-sway component and trolley positioning component. The objective of the first part is to suppress and eliminate the swings of hook and payload. Lyapunov techniques, LaSalle’s invariance theorem, and Barbalat’s lemma are used to demonstrate that the trolley can be driven to arrive at the desired position, while the unexpected hook swing and payload swing are damped out simultaneously with the proposed trajectory. Numerical simulation results indicate that the proposed control trajectory achieves superior performance and admits strong robustness against parameter variations and external disturbances.