Vertical and lateral heterostructures consisting of atomically layered two-dimensional (2D) materials exhibit intriguing properties, such as efficient charge/energy transfer, high photoresponsivity, and enhanced photocatalytic activities. However, the controlled fabrication of vertical or lateral heterojunctions on metal substrates remains challenging. Herein, we report a facile and controllable method for selective growth of WS/MoS vertical or lateral heterojunctions on polycrystalline gold (Au) foil by tuning the gas flow rate of hydrogen (H). We find that lateral growth is favored without H, whereas vertical growth mode can be switched on by introducing 8–10 sccm H. In addition, the areal coverage of the WS/MoS vertical heterostructures is tunable in the range of 12–25%. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) results demonstrate the quality and absence of cross-contamination of the as-grown heterostructures. Furthermore, we investigate the effects of the H flow rate on the morphology of the heterostructures. These pave the way to develop unprecedented 2D heterostructures towards applications in (opto)electronic devices.