Schiff base ligands such as methyl 4-[(2-butyl-4-chloro-5-formyl-1H-imidazol-1-yl)methyl]benzoate thiosemicarbazone (L-1) and 2-butyl-4-chloro-5-formylimidazole 2,4-dinitrophenylhydrzone (L-2) are designed and synthesized via the reaction between methyl 4-[(2-butyl-4-chloro-5-formyl-1H-imidazol-1-yl)methyl]benzoate & thiosemicarbazide for L-1 and 2-butyl-4-chloro-5-formylimidazole & 2,4-dinitrophenylhydrazine for L-2.Schiff bases are characterized by FT-IR, UV-visible, mass spectrometry, H-1 and C-13-NMR spectral studies. These ligands are individually tested for their antimicrobial activities for both gram positive and gram negative to examine their inhibition potential by well diffusion method. The corrosion inhibition property of all the three ligands L-1, L-2 & L-3 on mild steel in 0.5 N HCl solution has been investigated at different concentrations and different temperatures by weight loss method. The biological activity of L-2 has shown better activity against gram negative bacteria such as E-coli, Klebsiella pneumonia, Acinetobacter baumannii, Pseudomonas aeruginosa and gram positive bacteria Staphylococcus aureus when compared to standard ligand L-3. All the three ligands exhibit good corrosion inhibition property on mild steel in 0.5N HCl solution even at 0.1% concentration level and the rate of corrosion of mild steel is increased with increase of temperature of corrosion medium.