A voltage regulator includes an operational amplifier, a first transistor, a second transistor, a capacitor and a current sink circuit. The operational amplifier outputs a control voltage according to an amplified differential voltage between a first input terminal and a second input terminal of the operational amplifier. The first transistor includes a control terminal receiving the control voltage, a first terminal coupled to a supply terminal, a second terminal providing an output voltage, and a bulk terminal. The second transistor includes a second terminal coupled to the bulk terminal of the first transistor, and a bulk terminal coupled to the supply terminal. The capacitor includes a first terminal coupled to the bulk terminal of the first transistor, and a second terminal receiving the output voltage. The current sink circuit generates a feedback voltage according to the output voltage and output the feedback voltage to the operational amplifier.