A peptide/DNA nanocomplex was developed for the targeted delivery of chemotherapeutics and photosensitizers to cancer cells for efficient combination therapy. The chemotherapeutic drug doxorubicin (DOX) and the photosensitizer 5,10,15,20-tetra-(1-methylpyridine-4-yl)-porphyrin (TMPyP4) were physically incorporated by an aptamer (AS1411)-modified tetrahedral DNA nanostructure, where the tetrahedral DNA and aptamer-induced G-quadruplex provide binding sites of DOX and TMPyP4. The co-loaded 3A-TDN/DT displayed a targeted uptake by HeLa cancer cells through the high affinity and specificity between AS1411 and nucleolin, a protein overexpressed on many types of cancer cells. A polycationic polymer, mPEG-PAsp(TECH), was synthesized to complex with the DNA nanostructure to efficiently escape from lysosomes via the proton sponge effect upon the enhanced internalization by tumor cells. Under the irradiation of 660 nm laser light, TMPyP4 induced an upregulation of intracellular reactive oxygen species, which combined with DOX to fulfill the efficient inhibition of HeLa cells. Our study demonstrated a biocompatible peptide/DNA composite nanoplatform for combinational cancer therapy via the targeted delivery of therapeutic agents and efficient lysosomal escape.