Sensitive detection of cell necrosis is crucial for the determination of cell viability. Because of its high resolution at the cellular level and sensitivity, optical imaging is highly attractive for identifying cell necrosis. However, challenges associated with this technique remain present such as the rapid photobleaching of several types of organic fluorophores and/or the interference generated by biological autofluorescence. Herein, we synthesized novel biologically compatible Zn2+/Ln3+ metallacrowns (MCs) that possess attractive near-infrared (NIR) emission and are highly photostable. In addition, these MCs have the ability to label differentially necrotic HeLa cells from living cells. This work is also the first demonstration of (i) the use of the NIR emission arising from a single lanthanide(III) cation for optical biological imaging of cells under single photon excitation, (ii) the first example of a lanthanide(III)-based NIR-emitting probe that can be targeted to a specific type of cell.