K-Na co-doped δ-MnO？ (KNMOH) nanoflowers were synthesized, and their cytotoxic effects against HeLa cervical cancer cells were evaluated. The KNMOH exhibited significant dose- and time-dependent cytotoxicity at concentrations of 50 and 100 μg/mL. After 24 h of incubation treatment, cell viability decreased to (36.8±6.5)% and (33.4±6.4)% at 50 and 100 μg/mL, respectively. With extended exposure to 48 h, cell viability was (45.2±2.3)% and (32.3±2.8)% at the same concentrations. Phase-contrast microscopy revealed characteristic morphological changes including cell shrinkage and membrane blebbing formation, indicative of cell death. These findings demonstrate the potential of KNMOH nanoflowers as a cytotoxic agent for cervical cancer applications and provide a foundation for further mechanistic studies.