Hydrogels self-assembled by biologically based building blocks including peptides and proteins can be used as an ideal drug delivery platform and present great promise for biomedical applications. Herein, photodynamic antitumor therapy based on injectable N-fluorenylmethoxycarbonyl diphenylalanine (Fmoc-FF)/poly-L-lysine (PLL) hydrogels was achieved by encapsulation of the photosensitive drug Chlorin e6 (Ce6), as the hydrogels exhibit multiple favorable therapeutic features, including shear-thinning and self-healing properties, good biocompatibility, and perfect biodegradability. Such injectable hydrogels are shown to be well-suited for local injection and sustained drug delivery at the tumor site, especially toward therapy of superficial tumors. In vivo therapeutic results show that the tumor growth can be efficiently inhibited, especially under the strategy "once injection, multiple-treatments". During the whole treatment period, no detectable toxicity or damages to normal organs are observed. Therefore, the injectable hydrogels can be applied as a promising delivery platform for therapy of superficial tumors.