Near-infrared photothermal-activated nanomaterials are emerging as a promising tool in precise cancer theranostics. This Frontier article highlights the recent advances of photothermal-activated nanoagents in biomedical applications, namely photothermal-initiated drug/contrast agent release, gene silencing, programmed targeting and gas theranostics. In the end, we give a perspective on the further development of photothermal-sensitive nanomedicines.