This article presents a reliability-based topology optimization (RBTO) framework for the design of piezoelectric actuators, addressing the influence of material uncertainties on structural performance and operational reliability. Recognizing the sensitivity of piezoelectric structures to variability in material properties, this study integrates the joint optimization of material density and polarization distribution to enhance resilience under uncertain conditions. The proposed framework employs a Sequential Optimization and Reliability Assessment (SORA) method, coupled with a stochastic response surface model (SRSM), to efficiently manage the computational complexity typically associated with reliability analysis. The SORA approach significantly reduces computational cost compared to traditional double-loop methods, enabling faster convergence while preserving solution accuracy. Through numerical examples of piezoelectric actuators, the RBTO approach demonstrates improved design robustness compared to deterministic methods. The findings highlight the significant impact of material uncertainties, particularly in Young's modulus, on the optimized topologies, reinforcing the necessity of reliability-based approaches for advancing the performance of smart material systems.