Described is a voltage regulator with adaptive gain, which comprises: a plurality of power-gate transistors controllable by a digital bus, the plurality of power-gate transistors operable to provide a first power supply to a load, and to receive a second power supply as input; an analog-to-digital converter (ADC) to receive the first power supply and to generate a digital output representative of the first power supply; and a controller to receive the digital output representative of the first power supply and to generate the digital bus for controlling the plurality of power-gate transistors such that a transfer function of the plurality of power-gate transistors is substantially linear over an operating range.