Enzyme mimics have broad applications in catalysis and can assist elucidation of the catalytic mechanism of natural enzymes. However, challenges arise from the design of catalytic sites, the selection of host molecules, and their integration into active three-dimensional structures. Herein, we describe the development of a photooxidase mimic by synergetic molecular self-assembly. 9-Fluorenylmethyloxycarbonyl-l-histidine undergoes efficient co-assembly with phthalocyanine into nanovesicles with tunable particle size and membrane thickness. The obtained nanovesicles can be used as catalysts for reactive-oxygen-mediated photosensitive oxidation with improved efficiency and stability. This work highlights the co-assembly of simple building blocks into a supramolecular photocatalyst, which might give insight into possible evolutionary paths of photocatalytic membrane systems, and might allow facile transfer into photosensitive nanoreactors or artificial organelles.