Organic　framework　polymers　have　attracted　much　interest　due　to　the　enormous　potential　design　space　offered　by　the　atomically　precise　spatial　assembly　of　organic　molecular　building　blocks.　The　morphology　control　of　organic　frameworks　is　a　complex　issue　that　hinders　the　development　of　organic　frameworks　for　practical　applications.　Biomimetic　self-assembly　is　a　promising　approach　for　designing　and　fabricating　multiple-functional　nanoarchitectures.　A　bioinspired　hollow　flower-like　organic　framework　nanosphere　heterostructure　comprised　of　carbon　nitride　and　polydopamine　(g-C3N4@PDA)　is　successfully　synthesized　via　a　mild　and　green　method.　This　heterostructure　can　effectively　avoid　the　agglomeration　of　nanosheets　to　better　access　the　hollow　nanospheres　with　high　open-up　specific　surface　area.　The　electron　delocalization　of　g-C3N4　and　PDA　under　visible　light　can　largely　promote　photoelectron　transfer　and　enhance　the　photocatalytic　activity　of　the　g-C3N4@PDA.　Furthermore,　the　g-C3N4@PDA　can　effectively　enhance　the　generation　of　reactive　oxygen　species　under　irradiation,　which　can　lead　to　cell　apoptosis　and　enhance　the　performance　for　cancer　therapy.　Therefore,　the　as-prepared　g-C3N4@PDA　provides　a　paradigm　of　highly　efficient　photocatalyst　that　can　be　used　as　nanomedicine　toward　cancer　therapy.　This　study　could　open　up　a　new　avenue　for　exploiting　more　other　potential　hollow　nanosphere　organic　frameworks.　©　2019　WILEY-VCH　Verlag　GmbH　&　Co.　KGaA,　Weinheim