Combinatorial　photothermal　and　immunotherapy　have　demonstrated　great　potential　to　remove　primary　tumors,　suppress　metastases,　and　prevent　tumor　recurrence.　However,　this　strategy　still　confronts　patients　with　many　limitations,　such　as　complex　components,　sophisticated　construction,　and　inadequate　therapeutic　efficacy.　In　this　work,　small　molecules　of　porphyrin　derivatives　(PPor)　which　can　self-assemble　into　monodispersed　nanoparticles　without　supplement　of　any　other　ingredients　or　surfactants　are　developed.　The　formed　PPor　nanoparticles　(PPor　NPs)　exhibit　highly　photothermal　conversion　efficiency　of　70%　and　NIR-II　luminous　abilities　originate　from　the　strong　intramolecular　charge　transfer　(ICT)　effect　of　D-A　structure　under　808 nm　laser　irradiation,　thus　achieving　NIR-II　fluorescence　imaging　guided　photothermal　therapy　(PTT)　against　primary　tumors　with　a　high　cure　rate.　More　importantly,　tumor-associated　antigens　(TAAs),　together　with　damage-associated　molecular　patterns　(DAMPs)　released　from　PTT-treated　cancer　cells,　are　proved　to　elicit　immune　responses　to　some　degree.　After　combination　with　programmed　cell　death-1　(PD-1)　antibodies,　a　robust　systematic　antitumor　immunity　is　generated　to　restrain　both　primary　and　abscopal　tumors　growth,　prolong　survival,　and　prevent　pulmonary　metastasis　on　an　aggressive　4T1　murine　breast　tumor　model.　Thus,　this　study　provides　a　promising　therapeutic　paradigm　with　porphyrin　derivatives　nano-assembly　as　phototheranostic　agents　for　the　treatment　of　aggressive　tumors　with　high　efficiency.　©　2022　Wiley-VCH　GmbH.