Two-dimensional (2D) materials have received enormous attention as photocatalysts for hydrogen production to address the worldwide energy crisis. In this study, we employed first-principles computations to systematically investigate the structural, opto-electronic, and photocatalytic properties of novel GeC-MX2 (M = Mo, W, X = S, Se) van der Waals (vdW) heterostructures for photocatalysis applications. Our results reveal that the GeC-MX2 heterostructures can absorb visible light. The type-II band alignment in GeC-MoS2 and GeC-WS2 enables the photogenerated electron-hole pairs to be separated continuously. The electron transfer from the GeC monolayer to MX2 monolayer leads to a large built-in electric field at the interface. This induced electric field is essential for preventing the recombination of photogenerated charges. Moreover, the band-edge locations suggest that GeC-MX2 heterostructures can be utilized as a photocatalyst for water splitting. Finally, the opto-electronic properties of these novel GeC-MX2 heterostructures facilitate their practical utilization in future photocatalysis applications.