This paper considers a novel extremum seeking control with fractional-order switching technique (ESC-FOST) as a maximum power point tracking (MPPT) algorithm for a PV system. The proposed ESC-FOST combines extremum seeking controller with FO sliding mode dynamics, in which FO proportional-integral (PI) switching surface is adopted. The ESC-FOST can not only guarantee the output power is maintained around the maximum power point but that it will also have a faster tracking performance and higher accuracy than the ESC with integer-order switching technique (ESC-IOST). Simulation and experimental results demonstrate the effectiveness and benefit of the ESC-FOST for the PV plant.