Escherichia　coli　(E.　coli)　DH5α　has　been　recognized　as　a　non-pathogenic　bacterial　strain　with　tumor　colonization　ability.　However,　whether　such　a　bacteria-driven　drug-delivery　system　can　improve　the　targeting　of　tumor　therapy　or　not　remains　essentially　untouched.　Herein,　a　series　of　zinc　phthalocyanine　(ZnPc)　photosensitizers　with　different　numbers　of　charges　were　prepared　and　their　electrostatic　adhesion　properties　on　E.　coli　were　investigated　via　measuring　their　fluorescence　intensities　by　flow　cytometer.　Among　these　ZnPc　photosensitizers　investigated,　the　ZnPc　conjugate　with　four　positive　charges　(named　ZnPc-IR710)　exhibited　the　highest　loading　capacity　and　the　best　fluorescence　imaging　performance　of　E.　coli.　With　the　help　of　E.　coli,　E.　coli@ZnPc-IR710　presented　a　significantly　enhanced　cytotoxicity　on　human　breast　cancer　MCF-7　cells　compared　with　ZnPc-IR710　(survival　rate　of　tumor　cells　was　39%　vs.　57%　at　a　concentration　of　50　nmol　L−1).　Moreover,　in　vivo　study　showed　that　E.　coli@ZnPc-IR710　remarkably　inhibited　the　tumor　growth　and　resulted　in　a　complete　tumor　growth　suppress　in　subcutaneous　mouse　4T1　breast　tumor　model.　These　results　demonstrated　the　great　promise　of　bacterial-guided　photodynamic　therapy　(PDT)　in　the　treatment　of　solid　tumors,　and　provide　a　unique　strategy　to　enhance　the　antitumor　efficacy　of　PDT　by　utilizing　bacterial　vectors　in　tumors.　©　2020,　Science　China　Press　and　Springer-Verlag　GmbH　Germany,　part　of　Springer　Nature.