Surface modification is crucial in improving catalyst activity, since all catalytic reactions occur on the surface of the catalyst. This review discusses the application of nonthermal plasmas (NTP) for surface modification and functionalization of heterogeneous photocatalysts. NTP pretreatment provides an environmentally friendly and effective means for functionalization, surface etching, and/or defect regulation on the surface of photocatalysts. The correlations between modification variables and the properties of catalysts are reviewed in depth. Moreover, insights into the modification mechanisms are reviewed to provide state-of-the-art understanding and suggest that more advanced modification can be achieved. Finally, challenges and perspectives for future studies are provided.