Photodynamic　therapy　(PDT)　has　the　characteristics　of　being　simple　and　non-invasive,　and　with　on-demand　light　control.　However,　most　photosensitizers　exhibit　strong　hydrophobicity,　low　quantum　yields　in　water　and　low　tumor　selectivity.　In　this　study,　carbon　network-hosted　porphyrins　(CPs)　with　high　biocompatibility　and　efficient　singlet　oxygen　(1O2)　generation　were　developed　to　reduce　the　biotoxicity　of　photosensitizers　and　avoid　quenching　caused　by　hydrophobic　aggregation　for　enhanced　PDT.　The　CPs　were　prepared　by　a　simple　solid-phase　synthesis　method　using　porphyrin,　green　non-toxic　citric　acid　and　urea　as　the　raw　materials.　The　CPs　exhibited　excellent　water　solubility　and　high　biocompatibility.　Even　when　the　concentration　reached　1.5　mg　mL−1,　cells　still　had　good　biological　activity.　By　separately　fixing　the　porphyrins　in　the　carbon　network,　the　CPs　avoided　aggregation-induced　inactivation　and　had　high　generation　efficiency　of　1O2.　Furthermore,　in　order　to　improve　the　PDT　effect,　the　CPs　were　modified　with　the　upper　nuclear　targeting　peptide　TAT　(T-CPs),　which　was　used　to　target　the　nucleus　and　generate　1O2in　situ　to　directly　destroy　genetic　material.　The　proposed　strategy　provides　a　simple　and　green　path　to　prepare　nanophotosensitizers　with　high　biocompatibility　and　efficient　1O2　generation　for　PDT.　©　2023　The　Royal　Society　of　Chemistry.