Proton exchange membrane fuel cells (PEMFCs) are promising power sources owing to their high-power/energy densities and low pollution emissions. With the increasing demand for electricity for various low-power devices, small-scale storage of electricity encountered bottle-neck, which provides new opportunities for PEMFC. Owing to the high specific energy of PEMFCs, the utilization of this technology for small-scale applications has recently attracted significant attention. In recent years, considerable effort has been made to advance PEMFC technology and applications, especially in the small-scale PEMFC commercial market. The current review provides a holistic overview of the cutting-edge developments of small-scale PEMFCs in the transportation, stationary, and portable power generator fields. In particular, we examine current literature on the development of small-scale PEMFCs and discuss the operating complexity of PEMFC systems for different applications. Finally, we provide a forward-looking perspective on the strategies for small-scale high-specific-power PEMFC systems.