The study investigated the cytoactivities of methanolic leaf extract (MLE) and fractions of Senecio biafrae, profiled, and elucidated their metabolites. Hydromethanolic extract of S. biafrae obtained by maceration was partitioned and subjected to cytotoxicity using brine shrimp lethality assay (BSLA), human cervical adenocarcinoma (HeLa) and prostate cancer cell (PC3) lines. The bioactive principles of most active fractions were profiled using GC-MS. The dichloromethane fraction (DMF) was purified using column and high-performance liquid chromatography to afford compounds 1 and 2 identified by 1H and 13C, DEPT-90, DEPT-135, COSY, NOESY and EIMS spectra. The MLE and its fractions exhibited good toxicity on nauplii brine shrimp. The HF exhibited a pronounced cytoactivity on PC-3 cell line with 92.8% followed by DMF. The GC-MS profiling of HF and DMF identified 17 and 6 constituents respectively comprising saturated and unsaturated fatty acids, diterpenoidal alcohol, phytol and aromatic compounds. Hexadecanoic acid, cis, cis, cis-9, 12, 15-octadecatrienoic acid, and phytol accounted for the highest percentage of the constituents in both fractions. Structure elucidation confirmed compounds 1 and 2 as stigmasterol and ergosterol with cytoactivity which compared favourably with doxorubicin. The study revealed that S.biafrae contains cytotoconstituents evidenced by proliferation inhibition of HeLa and PC-3 cell lines. The cyto-activities and bioconstituents indicate that S.biafrae has the potential to be considered as a candidate for drug development in the management of cancer-related conditions. Further investigation into the specific bioactive compounds and their mechanisms of action could provide valuable insights into the therapeutic potential of S.biafrae in cancer treatment.