Schiff base derived from the condensation of 3-(p-bromophenyl)-1-phenyl-1H-pyrazolecarboxaldehyde with 4-amino-3-mercapto-1,2,4-triazin-5-one and its Co(II), Ni(II), Cu(II) and Zn(II) metal complexes have been synthesized in 1:1 and 1:2 molar ratios. Ligand and its metal complexes are characterized by various physicochemical techniques. On the basis of these techniques, octahedral geometry deduced for Co(II), Ni(II) and Zn(II) complexes and square planar for Cu(II) complexes. Low molar conductance values of all the metal complexes reveal their non-electrolytic nature. All the synthesized complexes have been screened in vitro for antibacterial activity against S. aureus, B. subtilis, P. aeruginosa and E. coli and antifungal activity against C. albicans and S. cerevisiae. It has been found that metal complexes show promising biological activity as compared to ligand. Schiff base and its metal complexes have been screened against human breast cancer cell lines by using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. In vitro anticancer cell lines results indicate that metal complexes exhibit significant activity on MCF-7.