Phototherapeutic　nanoplatforms　that　combine　photodynamic　therapy　(PDT)　and　photothermal　therapy　(PTT)　with　the　guidance　of　photoacoustic　(PA)　imaging　are　an　effective　strategy　for　the　treatment　of　tumors,　but　establishing　a　universal　method　for　this　strategy　has　been　challenging.　In　this　study,　we　present　a　supramolecular　assembly　strategy　based　on　Forster　resonance　energy　transfer　to　construct　a　supramolecular　nanostructured　phototherapeutic　agent　(PcDA)　via　the　anion　and　cation　supramolecular　interaction　between　two　water-soluble　phthalocyanine　ramifications,　PcD　and　PcA.　This　approach　promotes　the　absorption　of　energy,　thus　enhancing　the　generation　of　reactive　oxygen　species　(ROS)　and　heat　by　PcDA,　improving　its　therapeutic　efficacy,　and　overcoming　the　low　photon　utilization　efficiency　of　conventional　PSs.　Notably,　after　the　intravenous　injection　of　PcDA,　neoplastic　sites　could　be　clearly　visualized　using　PA　imaging,　with　a　PA　signal-to-liver　ratio　as　high　as　11.9.　Due　to　these　unique　features,　PcDA　exhibits　excellent　antitumor　efficacy　in　a　preclinical　model　at　a　low　dose　of　light　irradiation.　This　study　thus　offers　a　general　approach　for　the　development　of　efficient　phototherapeutic　agents　based　on　the　simultaneous　effect　of　PDT　and　PTT　against　tumors　with　the　assistance　of　PA　imaging.　A　nanostructured　supramolecular　phototherapeutic　agent　(PcDA)　was　developed　based　on　the　Forster　resonance　energy　transfer　mechanism.　PcDA　can　enable　the　visualization　of　a　tumor　with　a　photoacoustic　signal-to-liver　ratio　as　high　as　11.9,　and　95%　of　tumor　growth　is　suppressed　through　photodynamic　and　photothermal　synergistic　therapy　at　a　PcDA　dose　of　0.8　nmol　g-1　and　a　light　dose　of　300　J　cm-2.　image