Direct cellular production of topologically complex proteins is of great interest both in supramolecular chemistry and protein engineering.Wedescribe the first cellular synthesis of protein catenanes through the use of the p53 dimerization domain to guide the intertwining of two protein chains and SpyTag-SpyCatcher chemistry for efficient cyclization. The catenane topology was unambiguously proven by SDS-PAGE, SEC,a nd partial digestion experiments and was shown to confer enhanced stability toward trypsin digestion relative to monomeric control mutants.T he assembly-reaction synergy enabled by protein folding and genetically encoded protein chemistry offers ac onvenient yet powerfula pproach for creating mechanically interlocked, complex protein topologies in vivo.