<p>2, 2-dihydroxyindane-1, 3-dione(ninhydrin) and oxalyldihydrazide based Schiff base (SB) ligand and its transition metal complexes were prepared, isolated, and characterized by various spectral and analytical methods. Ligand coordinates in 1:1 ligand to metal ratio as a tetradentate (NN'OO'-donor) in all the complexes favored by obtained analytical results. Molar conductance values (15–25 Ω⁻¹cm²mol⁻¹) suggest the non-ionic nature of complexes. Thermal analysis displayed that the complexes are thermally more stable than ligands. Cobalt complex reported with higher catalytic activity, whereas the copper and zinc complexes exhibited stronger antioxidant activity. The antifungal activity was performed against five plant pathogenic fungi viz., <i>Fusarium oxysporum</i>, <i>Fusarium solani, Macrophomina phaseolina, Alternaria alternata</i>, and <i>Rhizoctonia solani,</i> and the results revealed excellent antifungal activity with all the complexes. Antibacterial activity was also done with five gram-positive bacteria namely, <i>Streptococcus mutans</i>, <i>Streptococcus pyrogenes</i>, <i>Streptococcus viridans</i>, <i>Corynebacterium diphtheriae</i> and <i>Corynebacterium xerosis</i> and three gram-negative bacterial strains, <i>Escherichia coli</i>, <i>Klebsiella pneuomoniae</i> and <i>Pseudomonas aeruginosa</i>. Cu(II) complex and Zn(II) complex were found to be the most active antimicrobial complexes and showed maximum inhibition of fungi as well as bacteria. The anthelmintic activity of compounds was also performed using <i>Pheretima posthuma,</i> and the compounds were also found to be anthelmintic. Current research on SB metal complexes forms a strong basis in the development of new metal-based therapeutics and in the investigation of biomedical uses of SB complexes.</p>