Abstract Actuators designed using piezoelectric materials are widely used in micro-robotic systems. Although topology optimization (TO) is a systematic design approach with the potential to conceive a novel piezoelectric actuator, the optimality of the design cannot be guaranteed unless the material uncertainties resulting from complex fabrication are considered. Therefore, this study presents the optimal design of a piezoelectric actuator and investigates the impact of uncertainties on the designed layout. Specifically, this study introduces material uncertainties through Young’s modulus and the piezoelectric coefficient individually and concurrently, thus facilitating a comprehensive exploration of design robustness. The density-based TO method used in this study incorporates the spatial distribution of material densities and polarities within the domain. To evaluate the robustness of the results of the proposed method, a thorough comparison with the Monte Carlo method results was conducted, revealing not only the robustness of the designed layouts but also enhanced computational efficiency.