The excellent physical features of two-dimensional (2D) layered materials make them very promising for electronic and optoelectronic applications. Here, we investigated the gate-tunable and broadband (220, 365, 460, 510, 840 and 1020 nm) photoresponse of MoSe2 transistor with metallic (Cr–Au/MoSe2) and van der Waals (vdWs) hetero MoSe2/WTe2 contacts. Our study intends to investigate the underlying mechanism of photogeneration and carrier's transport process by Cr–Au/MoSe2 and hetero MoSe2/WTe2 contacts in the MoSe2 transistor. Since, our research revealed that MoSe2 devices with hetero MoSe2/WTe2 contacts exhibited remarkable performance, including high responsivity (R) of about 11.23 × 105 mA/W, exceptional external quantum efficiency (EQE) of 6.3 × 105 %, and detectivity (D*) of 4.61 × 1010 Jones compared to metallic contacts. This implies that the enhanced performance of our devices with 2D hetero-contacts could be attributed to reduced contact resistance, interlayer charge transfer and interlayer excitons in MoSe2/WTe2 heterostructure. Also, the gate-controlled response and broadband capabilities of van der Waals 2D heterostructures hold significant promises for a wide range of optoelectronic applications, including photodetectors, optical sensors, and visual imaging systems.