This application provides an optical signal processing circuit and an electronic device, to improve a signal-to-noise ratio of an output signal of a fingerprint sensor, thereby improving a fingerprint recognition rate. The optical signal processing circuit includes a photosensitive device, an amplifier transistor T1, a switch transistor T2, a switch transistor T3, a readout circuit, a control circuit, and a voltage-adjustable power supply. When the optical signal processing circuit is in a compensation reset phase, the voltage of the gate of T1 exactly reaches a level at which the amplifier transistor T1 is turned on. Therefore, when an input voltage and a voltage increment are applied to the gate of T1, a gate-source voltage Vgs of T1 increases, and T1 amplifies an input voltage signal to generate an output signal.