Tremendous interest in self‐assembly of peptides and proteins towards functional nanomaterials has been inspired by naturally evolving self‐assembly in biological construction of multiple and sophisticated protein architectures in organisms. Self‐assembled peptide and protein nanoarchitectures are excellent promising candidates for facilitating biomedical applications due to their advantages of structural, mechanical, and functional diversity and high biocompability and biodegradability. Here, this review focuses on the self‐assembly of peptides and proteins for fabrication of phototherapeutic nanomaterials for antitumor photodynamic and photothermal therapy, with emphasis on building blocks, non‐covalent interactions, strategies, and the nanoarchitectures of self‐assembly. The exciting antitumor activities achieved by these phototherapeutic nanomaterials are also discussed in‐depth, along with the relationships between their specific nanoarchitectures and their unique properties, providing an increased understanding of the role of peptide and protein self‐assembly in improving the efficiency of photodynamic and photothermal therapy. Self‐assembled peptide‐ and protein‐based nanomaterials are important and promising for the novel and emerging antitumor techniques of photodynamic therapy and photothermal therapy. Recent advances in fabrication and application of phototherapeutic nanomaterials based on peptide and protein self‐assembly are highlighted, providing an increased understanding of the role of peptide and protein self‐assembly in improving the efficiency of antitumor phototherapies.