Two-dimensional (2D) materials as contacts for semiconductor devices have attracted much attention due to minimizing Fermi level pinning. Schottky–Mott physics has been widely employed to design 2D material-based electrodes and to elucidate their contact behavior. In this study, we revealed that charge transfer across a 2D/semiconductor heterointerface and materials characteristics besides work function should be accounted for in fabrication of electrodes based on 2D materials. Our density functional theory (DFT) calculations predicted that charge transfer between ZnO and NbSe2 lowers the barrier height at the heterojunction and that conductive surface states of ZnO provide an additional conduction channel in the ZnO/NbSe2 heterostructures. Crystalline ZnO/NbSe2 heterostructures were prepared by the hydrothermal method. Electrical characterizations of the ZnO/NbSe2 heterostructures showed Ohmic-like behavior as predicted by the DFT calculations, opposed to the prediction based on the Schottky–Mott model.