AbstractThe synthetic difficulty of target‐specific lanthanide complexes, despite their unique characteristics, limits their use in in vitro/ in vivo studies and biomedical applications. With commercially available and affordable reagents, a facile synthetic approach is developed to modularly deploy nitrobenzoxadiazole and neodymium complexes onto bioactive peptides. The yielded probes show observable neodymium emission with specific localization to corresponding biotargets in vitro, which became the first example of a stable, water‐soluble, and target‐specific neodymium(III) complex applicable for in vitro imaging with detectable brightness.