Recently, photothermal therapy (PTT) which employs light-induced heating to destroy cancer tissues/cells has received tremendous attention due to its improved selectivity and minimal invasion to surrounding healthy tissues. A variety of photothermal conversion agents (PTCAs) with high near-infrared (NIR) light absorbance have been widely explored for NIR light-induced PTT. However, many of them cannot be used directly in vivo owing to their nonbiodegradability, immunogenicity, poor pharmacokinetics, or potential long-term toxicity. Proteins and peptides with inherent biocompatibility and biodegradability have been used as delivery vehicles for PTCAs or used as biotemplates to direct the synthesis of PTCAs. In this review, we will summarize recent advances in the development of protein/peptide-based photothermal cancer theranostics. The perspectives and challenges of these nanoplatforms will also be discussed.