This work reports the impact of ZnO layer thickness on optical and resistive switching behavior of BaTiO₃/ZnO heterostructures grown by pulsed laser deposition. The interface polarization coupling becomes more efficient and causes a remarkable change in heterostructure properties with decrease in ZnO layer thickness. The heterostructure with ZnO thickness of 25 nm displays the enhanced resistive switching characteristics with switching ratio ≈10⁶ and good stability in low and high resistance states. Moreover, the photoluminescence spectrum exhibits two additional blue emissions when ZnO thickness is ≤50 nm and their mechanism is highlighted based on interface band offset and interface polarization coupling effect.