A sensor, a manufacturing method thereof and an electronic device. The sensor includes: a base substrate; a thin-film transistor (TFT) disposed on the base substrate and including a source electrode; a first insulation layer disposed on the TFT and provided with a first through hole running through the first insulation layer; a conductive layer disposed in the first through hole and on part of the first insulation layer and electrically connected with the source electrode via the first through hole; a bias electrode disposed on the first insulation layer and separate from the conductive layer; a sensing active layer respectively connected with the conductive layer and the bias electrode; and an auxiliary conductive layer disposed on the conductive layer. The sensor and the manufacturing method thereof improve the conductivity and ensure normal transmission of signals by arranging the auxiliary conductive layer on the conductive layer without addition of processes.