A bandgap reference circuit includes a current generating circuit, a switch circuit and a control circuit. The current generating circuit is triggered by a trigger signal generated when the bandgap reference circuit starts up. The current generating circuit is arranged to generate a reference current according to the trigger signal. The switch circuit is controlled by a switch control signal to be selectively coupled between the current generating circuit and a regulator. The switch circuit is arranged to, when coupled between the current generating circuit and the regulator according to the switch control signal, provide a bandgap voltage to the regulator according to the reference current. The control circuit is coupled to the current generating circuit and the switch circuit, and is arranged to generate the switch control signal according to the trigger signal.