New Pd/Pt-complexes were synthesized by incorporating α-keto stabilized unsymmetrical phosphorus ylides [Ph₂P(CH₂)_nPPh₂C(H)C(O)C₆H₄-p-Ph] (n = 1, (Y¹); n = 2, (Y²)) and M(Cod)Br₂ (M = Pt, Pd; Cod = 1,5-cyclooctadiene). The obtained P,C-chelated [PdBr₂(κ²-Y¹)] (1), [PtBr₂(κ²-Y¹)] (2), [PdBr₂(κ²-Y²)] (3), and [PtBr₂(κ²-Y²)] (4) complexes were characterized successfully by FT-IR and NMR (¹H, ¹³C, and ³¹P) spectroscopic methods. The structures of 1, 2, and 3 were elucidated by single crystal X-ray structural analyses. The structures of 1 and 2 consist of five-membered rings, while that of 3 has a six-membered ring, formed by coordination of the ligand with the phosphine group and the ylidic carbon atom to the metal center. Moreover, the cytotoxic effects of the compounds were studied by a MTT assay in three human carcinoma cell lines: A2780, H1299, and U87 MG. The compounds proved to be outstanding potent cytotoxic agents against the A2780 cell line and can be considered as a promising lead in cancer-treating drug discovery and development. Also, these newly synthesized compounds were evaluated for their in vitro antioxidant and antifungal activities by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging and potato dextrose agar (PDA) medium, respectively. The results showed that these compounds exhibited excellent biological activities.