The most emerging 2D-materials-based heterostructures are considered promising candidates because of their multifunctional logic applications for electric and optoelectronic devices. Here, a high gate tunable rectification in van der Waals heterostructure composed of n-type rhenium disulfide (n-ReS₂) and p-type germanium selenide (p-GeSe), using pure Ohmic contacts, is reported. The large rectification ratio (RR) deprived of any Schottky contribution is tuned up to 4 × 10⁵ because of the sharp interface of p-GeSe and n-ReS₂. The sheet-thickness effect over the rectification is also observed in the p-GeSe/n-ReS₂ heterostructure as well. The profound photovoltaic measurements under lights of different power intensities depict a high photo responsivity of 3.9 × 10³ A W⁻¹ with an external quantum efficiency of 87% and specific detectivity (D* = 1.5 × 10¹²). The fast growth (16.6 µs) and decay times (12.3 µs) are extracted by the exponential rise and decay fitting. Moreover, practical applications of the p-GeSe/n-ReS₂ heterostructure devices are exhibited by observing inverter behavior and high-frequency switching operations, which is also the breakthrough of this research. Fabrication of such smart devices based on transition metal dichalcogenides (TMDs) van der Waals heterostructures may enhance the energy harvesting as well as the multifunctional logic switches.