2D semiconductors have attracted considerable interest in the quest to overcome some of the challenges associated with 3D bulk semiconductors. The application of 2D semiconductors in transistor-based electronic devices requires a reliable patterning technology with thickness controllability for continued transistor scaling. In this study, a facile synthesis approach is developed that allows direct patterning of transition metal dichalcogenides (TMDs) with thickness controllability at the wafer scale through intergranular diffusion-assisted liquid-phase chemical vapor deposition using a sacrificial metal layer. By depositing a liquid-phase transition metal precursor onto the pre-patterned polycrystalline Ni/SiO2 substrate, a directly patterned transition metal layer can be formed on SiO2 via intergranular diffusion through the Ni grain boundaries, enabling the growth of patternable TMDs with a controllable thickness. The as-synthesized directly patterned WS2 transistor exhibits typical n-type transport behavior with a stable photoswitching performance. The proposed patterning technique can make the application of 2D semiconductors in advanced electronic devices more viable.