Photothermal catalysis integrates the strengths of photocatalytic and thermochemical processes and has gained significant attention in driving energy-consuming reactions such as CO 2 reduction and pollutant decomposition. It is of particular interest for efficient utilization of the full solar spectrum via capturing shorter-and longer-wavelength light for photocatalysis and photothermal conversion, respectively. As this rapid-growing research area begins to raise and answer fundamental questions about constructing photothermal catalytic systems, now is the time to summarize the recent progress and delineate the potential directions. In this review, we first categorize the mechanisms of photothermal effects into three types based on the different mechanisms of heat generation. We also present a comprehensive overview of the recent advancements in photothermal nanomaterials, with particular emphasis on elucidating their fundamental mechanisms as efficient light-to-heat converters. We then discuss the representative environmental applications of photothermal catalysis. Finally, we briefly outlined the frontier challenges and delineated prospective solutions for the future development of efficient photothermal catalytic nanomaterials.