Hydrogen peroxide (H2O2) is an essential green oxidant with widespread industrial applications, yet its conventional production methods remain energy-intensive and environmentally burdensome. Herein, we report a facile hydrothermal synthesis of CdS nanorods decorated with ZnS nanodots as an efficient piezocatalytic system for sustainable H2O2 production in pure water. The designed CdS/ZnS heterostructure integrates the piezoelectric properties of ZnS with the narrow band gap of CdS, facilitating enhanced charge separation and catalytic activity under ultrasonic excitation. Structural and morphological analyses confirm the uniform decoration of ZnS nanoparticles on CdS nanorods, forming a well-defined type-II heterojunction with favorable band alignment. The optimized catalyst (CdS/ZnS-1) exhibits good piezocatalytic performance, achieving a high H2O2 production rate (369.3 µmol g−1 h−1) under 45 kHz ultrasonic frequency, which is attributed to optimal cavitation effects and interfacial charge transfer. Mechanistic studies reveal that dissolved oxygen and piezo-generated holes play pivotal roles in the reaction, while electrochemical and spectroscopic analyses demonstrate efficient charge separation and reduced recombination in the heterostructure. Furthermore, the catalyst maintains excellent stability and recyclability over multiple cycles, underscoring its potential for practical applications. This work not only provides a novel strategy for designing high-performance piezocatalysts via heterojunction engineering but also advances the sustainable synthesis of H2O2 using mechanical energy, contributing to green chemistry and environmental remediation.