Schiff bases are important class of organic ligand, which played an integral role in the expansion of coordination chemistry and various aspects of biocoordination chemistry. Four new mononuclear Schiff base transition metal complexes [MLaLbX], (where M = Cu(II), Ni(II), Zn(II) and Co(II); La = Schiff base ligand derived from L-tyrosine and 2’-hydroxyacetophenone; Lb = N,N,N’,N’-tetramethylethylene-1,2-diamine; X = H2O) have been synthesized. The synthesized transition metal complexes were characterized by molar conductance, elemental analyses and spectral studies such as UV-Vis., FTIR and EPR. Non-electrolytic nature of the complexes was confirmed by molar conductance. Tridentate coordination nature of the Schiff base ligand was confirmed by FTIR spectra. In vitro antimicrobial studies were carried out against bacterial strains such as S. aureus, Bacillus, E. coli, and P. aeruginosa and fungal strains such as A. flavus, Rhizopus and Mucor. The mosquito larvicidal activity was performed against Culex quinquefasciatus for the Schiff base ligand and the synthesized metal complexes.