Two new cytotoxic fluorescent platinum(II) compounds, cis-[Pt(A9opy)Cl-2] (1) and cis-[Pt(A9pyp)(DMSO)Cl-2] (2), have been designed, synthesized, and characterized by IR, H-1 NMR, and Pt-195 NMR spectroscopy; electrospray ionization mass spectrometry (ESI-MS); and single-crystal X-ray diffraction. The carrier ligands selected for the synthesis of these fluorescent platinum(II) compounds are E-2-[1-(9-anthryl)-3-oxo-3-prop-2-enylpyridine) (abbreviated as A9opy) and E-1-(9-anthryl)-3-(2-pyridyl)-2-propenone (abbreviated as A9pyp). The compound cis-[Pt(A9opy)Cl-2] (1) comprises a peculiar cis-platinum(II) organometallic compound, in which the platinum(II) ion is bound to the photoisomerizable carbon-carbon double bond of the carrier ligand. The effects of the metal-ion coordination on the photoisomerization of the carbon-carbon double bond of the ligand have been studied. In contrast, the carrier ligand A9pyp used for the synthesis of the cis-[Pt(A9pyp)(DMSO)Cl-2] compound (2) does not undergo such an isomerization process and remains in the E conformation, while coordinated to the platinum(II) ion through the nitrogen of the pyridine ring. In addition to the synthesis and characterization, solution studies of both compounds have also been performed in detail, including NMR and ESI-MS spectroscopy. Moreover, a high degree of cytotoxic activity of compound 1 was found, as compared to cisplatin and its corresponding platinum-free molecule, in a series of human tumor cell lines. Compound 2 was also found to be highly active against these cell lines but appeared less active compared to the platinum-free molecule.