As suspensions critically affect the ride and handling performance of vehicles, considerable efforts have been made to improve their design by an optimization method. In this paper, we propose a topology optimization–based method for suspension synthesis by using a 3‐dimensional model constructed with nonlinear bars and zero‐length springs that discretize the 3‐dimensional space between the chassis frame and a vehicle wheel. For optimization, bar cross‐sections and spring stiffness values are used as design variables alongside the nodal positions of bar elements as shape optimization variables to simultaneously optimize the topology and shape. To verify the proposed approach, 2 types of design problems were solved: recovering known suspension mechanisms for a given set of wheel trajectories and synthesizing unknown suspension mechanisms that satisfy several design constraints typically used in the automobile industry. Through these examples, possibilities to design new and advanced suspensions by the proposed optimization method are clearly demonstrated.