Biomolecular hydrogels assembled from biomolecules, such as proteins, peptides, and polysaccharides, are promising candidates for facilitating biomedical applications due to their advantages of high biocompatibility, adjustable mechanical properties, functional diversity, and good degradability. This review focuses on current progress in the field of supramolecular injectable biomolecular hydrogels and their applications in antitumor photodynamic therapy (PDT), photothermal therapy (PTT), combined PDT and PTT, and antibacterial phototherapy with emphasis on biomolecular hydrogelators, injectable behaviors, phototherapeutic functions, and the remaining challenges. We hope that this review can provide useful inspiration for the construction and biological applications of novel photo-functional hydrogels as well as phototherapies.