Herein, we present a water-soluble dendritric Pt(II) complex as a phosphorescent label for bacterial cells. The dendritic moiety endows the Pt(II) complex with unique properties such as water solubility, shielding from quenching by dioxygen, and binding to bacterial surfaces. The new biosensor was employed for two-photon excitation microscopy, and the binding was confirmed by electron microscopy, which demonstrates that such hybrid arrays can provide orthogonal yet complementary readouts.