Most　existing　photosensitizers　(e.g.,　porphyrins)　are　often　aggregated　in　aqueous　solution　because　of　their　large　conjugated　molecular　structures.　This　aggregation　usually　results　in　a　lack　or　low　levels　of　reactive　oxygen　species　(ROS)　generation　due　to　aggregation-caused　quenching,　which　severely　hampers　the　application　of　photosensitizers　in　photodynamic　therapy　(PDT).　Herein,　we　make　an　interesting　finding　that　a　boronic　acid-functionalized　phthalocyanine　(PcN4-BA)　displays　an　uncommon　phenomenon,　an　aggregation-enhanced　photodynamic　effect.　The　combination　of　the　ability　to　form　uniform　nanostructured　self-assemblies　in　water,　highly　efficient　ROS　generation　and　boronic　acid-induced　targeting　give　PcN4-BA　excellent　performances　in　antimicrobial　PDT.　©　The　Royal　Society　of　Chemistry　2020.