In this paper, we present an integrated device in which an UV detector and a supercapacitor are built on the same vertical-aligned silicon nanowire (SiNW) array electrode. It is found that the embedded supercapacitor is of an impressive capacitance density of 13.6 F cm⁻³ and able to power the detector for more than 10 h with a single charge in less than 100 s. The fast and stable UV light responsivity of the detector has been demonstrated during the whole working period. This low cost high performance device has proved a type of promising applications in which a sensor is seamlessly integrated with a power source for its functions.