beta-Galactosidase (beta-gal) is an important biomarker for ovarian cancers. In this work, we designed and synthesized a novel iridium(III)-based probe 1 for discriminating ovarian carcinoma cell lines from normal cell lines. The probe could detect beta-gal even in the presence of a highly autofluorescent background. The probe also showed a good linear response to beta-gal between 0 and 30 U/mL, with a detection limit of 0.51 U/mL. Importantly, complex 1 could selectively "light up" ovarian carcinoma cells) while exhibiting negligible luminescence in normal cells. Overall, complex 1 could be potentially used as a useful probe for detecting beta-gal expression in the context of ovarian cancer diagnostics.