The present disclosure relates to an LED driving circuit and method using a single inductor. A constant current controller controls a power stage circuit to provide a constant output signal, and thus to provide a constant current signal for an LED load. A dimming controller regulates luminance of the LED load. A constant voltage generating circuit receives the current signal at an output terminal of the power stage circuit and a reserve supply voltage for providing a supply voltage for the dimming controller. Compared with the prior art, the present disclosure does not need an independent power supply chip, and reduces components such as inductors and rectifying transistors. Thus, a peripheral circuit is simplified, and an overall size of the system is reduced.