Metallic contacts are critical components of electronic devices and the presence of a large Schottky barrier is detrimental for an optimal device operation. Here, we show by using first-principles calculations that a self-assembled monolayer (SAM) of polar molecules between the metal electrode and MoSe₂ monolayer is able to convert the Schottky contact into an almost Ohmic contact. We choose –CH₃ and –CF₃ terminated short-chain alkylthiolate (i.e. SCH₃ and fluorinated alkylthiolates (SCF₃)) based SAMs to test our approach. We consider both high (Au) and low (Sc) work function metals in order to thoroughly elucidate the role of the metal work function. In the case of Sc, the Fermi level even moves into the conduction band of the MoSe₂ monolayer upon SAM insertion between the metal surface and the MoSe₂ monolayer, and hence possibly switches the contact type from Schottky to Ohmic. The usual Fermi level pinning at the metal–transition metal dichalcogenide (TMD) contact is shown to be completely removed upon the deposition of a SAM. Systematic analysis indicates that the work function of the metal surface and the energy level alignment between the metal electrode and the TMD monolayer can be tuned significantly by using SAMs as a buffer layer. These results clearly indicate the vast potential of the proposed interface engineering to modify the physical and chemical properties of MoSe₂.