A Schiff base ligand of N-methyl Thiosemicarbazide and its complexes with Co metal ion of binary [Co(L)2] (Complex-A), and ternary, formulae [Co(L)(L1)(H2O)] (Complex-B), [Co(L)(L2)(H2O)] (Complex-C) where L is Schiff base ligand, L1 is Bi-pyridine and L2 is oxalic acid have been synthesized and the compounds had been characterized based on the several spectroscopic results. The interaction of these compounds with DNA was investigated by electronic absorption spectroscopy and fluorescence spectroscopy. Our experiments indicated that these complexes could strongly bind to CT- DNA via intercalation mode with Kb values of 1.2 x 104 M -1 to 5.7 x 104 M -1 and the nucleotide incision against super coiled pBR322 DNA had been investigated by both photolytic and oxidative techniques to reveal the efficient manner of cleavage by the metal complexes. Furthermore, these complexes exhibited significant in vitro Cytotoxicity against HeLa & MCF7 cell lines showing IC50 values around 46.03 to 62.05 μM. Finally, an antimicrobial assay of these complexes over one gram-positive bacterium of Bacillus Subtilis and one gram-negative bacterium of Escherichia Coli and also two fungal species had given a good result.