We investigate the structural, electronic and optical properties of eight possible Zr2CO2/GaS van der Waals heterostructures using first-principles calculations. These structures display favorable stability, indicated by matching crystal structures and a negative formation energy (-6.57 eV). In all configurations, they act as indirect bandgap semiconductors with a type-II band alignment, allowing efficient electron- hole separation. Optical studies reveal their suitability for optoelectronic applications. Zr2CO2/GaS under 3% biaxial compressive strain meets the criteria for photocatalytic water splitting, suggesting their potential for electronic and optoelectronic devices in the visible spectrum. Our findings present prospects for advanced photocatalytic materials and optical devices.