In this study, we fabricated and characterized an InGaN/GaN multi-quantum-well (MQW)-based p-n junction photodetector (PD) for voltage-selective lightemitting and photo-detective applications. The photodetector exhibits a cutoff wavelength at around 460 nm which is close to its electroluminescence (EL) peak position. The rejection ratio was determined to be more than three orders of magnitude. Under zero bias, the responsivity of the device peaks at 371 nm, with a value of 0.068 A/W, corresponding to a 23% quantum efficiency. The overall responsivity gradually rises as a function of reverse bias, which is explained by the enhanced photocarrier collection efficiency.