Tungsten diselenide ((Formula presented.)) has emerged as a promising ambipolar semiconductor material for field-effect transistors (FETs) due to its unique electronic properties, including a sizeable band gap, high carrier mobility, and remarkable on–off ratio. However, engineering the contacts to (Formula presented.) remains an issue, and high contact barriers prevent the utilization of the full performance in electronic applications. Furthermore, it could be possible to tune the contacts to (Formula presented.) for effective electron or hole injection and consequently pin the threshold voltage to either conduction or valence band. This would be the way to achieve complementary metal–oxide–semiconductor devices without doping of the channel material.This study investigates the behaviour of two-dimensional (Formula presented.) field-effect transistors with multi-layer palladium diselenide ((Formula presented.)) as a contact material. We demonstrate that (Formula presented.) contacts favour hole injection while preserving the ambipolar nature of the channel material. This consequently yields high-performance p-type (Formula presented.) devices with (Formula presented.) van der Waals contacts. Further, we explore the tunability of the contact interface by selective laser alteration of the (Formula presented.) under the contacts, enabling pinning of the threshold voltage to the valence band of (Formula presented.), yielding pure p-type operation of the devices.