Ultrathin mesoporous Co3O4 nanosheets on a stainless steel mesh (SS-Co3O4) have been synthesized through an electrochemical deposition method. The SS-Co3O4 catalyst exhibits high photothermal performance, resulting in a considerable increase of temperature above the light-off temperature for VOC oxidation. Aerobic oxidations of propylene and propane under simulated sunlight were selected as probe reactions to explore the photo-/thermo-catalytic (PTC) activity. The results show that SS-Co3O4 with only 7 mg of Co3O4 grown on the substrate possesses superior PTC activity, which merely occurs around the directly grown SS-Co3O4 rather than the Co3O4 coated SS. The combined properties of SS-Co3O4 such as the ultrathin two-dimensional shape, foam-like porous inside architecture, and supported metal substrate could lead to the integrative advantages of the maximum utilization of photothermal conversion, more catalytically active sites, and enhanced amount and mobility of surface lattice oxygen species, resulting in excellent PTC activity of SS-Co3O4. This work provides insights into the rational design of monolith catalysts for the solar driven environmental purification and suggests new ideas toward the overall utilization of solar energy.