Abstract: With the continuous accumulation of refractory organic pollutants and antibiotics in aquatic environments, the development of efficient and sustainable water treatment technologies has become an important research focus in the field of environmental catalysis. Among emerging advanced oxidation technologies, piezocatalysis has attracted increasing attention because it can directly convert ubiquitous mechanical energy into chemical energy for reactive oxygen species (ROS) generation without requiring external light irradiation or additional oxidants. However, conventional piezocatalytic materials generally suffer from several intrinsic limitations, including weak piezoelectric polarization, rapid recombination of charge carriers, insufficient active sites, and sluggish interfacial reaction kinetics, which severely restrict their practical catalytic efficiency. In particular, although heterojunction engineering has been widely considered an effective strategy to improve charge separation, constructing highly efficient piezoelectric heterojunction systems with directional charge-transfer pathways and strong redox capability remains a major challenge. To address these issues, BiOCl/g-C₃N₄ (BOC/CN) composites were successfully synthesized via a hydrothermal method, and a tightly coupled Z-scheme heterojunction was rationally constructed through interfacial engineering. The phase structure, morphology, interfacial characteristics, charge-transfer behavior, and piezocatalytic performance of the composites were systematically investigated. The results demonstrate that BOC nanosheets are uniformly anchored onto the CN surface, forming an intimate and continuous heterointerface that effectively promotes interfacial charge migration and spatial charge separation. More importantly, the Z-scheme charge-transfer pathway preserves the strong oxidation ability of holes in the valence band of BOC and the high reduction ability of electrons in the conduction band of CN, thereby significantly enhancing the generation efficiency of ROS under ultrasonic stimulation. Benefiting from the synergistic effect between piezoelectric polarization and interfacial charge redistribution, the BOC/CN composite exhibits remarkably enhanced piezocatalytic activity toward tetracycline (TC) degradation. Under ultrasonic vibration, the degradation efficiency rate reaches 0.189 min⁻¹, which is 11.8 and 5.7 times higher than that of pure CN and BOC, respectively. Radical trapping experiments confirmed that holes (h⁺), hydroxyl radicals (·OH), and superoxide radicals (·O⁻ ₂) synergistically dominated the degradation process. In addition, BOC/CN displays excellent performance in piezocatalytic H₂O₂ synthesis, achieving a generation rate of 280 μmol/(L·h), which is significantly higher than those of pure BOC and CN (both close to 20 μmol/(L·h)). This enhanced H₂O₂ production is mainly attributed to the efficient two-electron oxygen reduction pathway enabled by the Z-scheme heterojunction and piezo-induced charge separation. This work deepens the understanding of piezoelectric Z-scheme interfacial mechanisms and provides a promising strategy for the design of highly efficient piezocatalysts for environmental remediation and sustainable energy conversion.