A new series of transition metal complexes of Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) have been synthesized from the Schiff base (L) derived from 5-bromo-3-hydrazonoindolin-2-one 3-((2-aminoethyl)amino)quinoxalin-2(1H)-one and 2,2-dimethyl-1,3-dioxane-4,6-dione. All the complexes were characterized in the light of elemental analysis, molar conductance, FT IR, UV-VIS, magnetic, thermal and powder XRD studies. Analytical data reveal that the Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) complexes possess 1:1 metal–ligand ratios. The ligand and its complexes have been screened for the antibacterial activities towards bacteria E. coli, P. vulgaris and S. pyogones, and antifungal activities towards fungi A. flavus, C. albicans and F. solani. The results of these studies revealed that the free ligand and its metal complexes showed significant antimicrobial potency. The DNA cleavage studies have also been carried out on Calf-thymus DNA and it is observed that these Co(II), Ni(II), Cu(II), Zn(II), Cd(II) shows complete DNA cleavage activity whereas Hg(II) show partial DNA cleavage in the presence of H2O2 and UV light.