In this paper, synthesis and characterization of metal complexes [Cu(L)]ClO (), [Ga(L)]NO·2HO () and [In(L)]NO·HO () (HL = 2-acetylpyridine (4)-phenylthiosemicarbazone) was carried out, including elemental analysis, spectral analysis (IR, UV-vis, NMR), and X-ray crystallography. Complex contains one S-bridged binuclear [Cu(L)] unit, where two Cu atoms display diverse coordination geometries: one being square planar geometry and the other octahedral geometry. Both and are mononuclear complexes, and the metal centers in and are chelated by two NNS tridentate ligands possessing a distorted octahedral geometry. Biological studies show that all the complexes possess a wide spectrum of modest to effective antibacterial activities and remarkable cytotoxicities against HepG2 cells, and , in particular, with an IC value of 0.19 ± 0.06 μM, is 113-fold and 28-fold more cytotoxic than HL and the antitumor drug mitoxantrone, respectively. In addition, exhibits excellent photoluminescence properties. Upon the addition of equiv of In ions, a remarkable fluorescence intensity of HL and fluorescent color change (from transparent to light-green) could be observed with 365 nm light, indicating that this ligand may be used as a promising colorimetric and fluorescent probe for In detection.