We have developed novel formazan dyes (18–23) of enhanced fastness properties with cost-effectiveness in an aqueous system, without employing any Buffers and organic solvents. Their development was entailed of the synthesis of 2-((phenyl (2-(4-sulfophenyl) hydrazono) methyl) diazenyl) benzoic acid followed by the diazotization of 2-aminobenzoic acid that further reacted with the 4-[(2Z)-2-benzylidenehydrazinyl] benzene sulfonic acid. The multi-chromic (1:1 and 2:1) metal complexes of 2-((phenyl (2-(4-sulfophenyl) hydrazono) methyl) diazenyl) benzoic acid had been developed with the salts of Cr, Fe, Co, Cu and Ni; and they were characterized by elemental analysis, powder X-ray crystallography, Ultraviolet–visible, Fourier transforms infrared, Proton nuclear magnetic resonance and C13-nuclear magnetic resonance spectroscopic techniques. Density functional theory (DFT) studies of all dyes (18–23) were performed to evaluate the most stable geometries and structural parameters as well. The synthesized formazan dyes were evaluated for their different fastness (light, wash, perspiration), exhaustion and fixation properties on goat leather fabric and were revealed to have virtuous fastness properties (3–5, 4–5, 3–5, and 4–5) with high percentage value of exhaustion and fixation ranged from 91 to 97% and 90–98% respectively. The synthesized formazan dyes (18–23) were developed different colors such as Red, Brown, Green, Black, and Blue on leather. Synthesized formazan dyes were also evaluated for their antibacterial propensity on leather substrate and in solution by agar well diffusion method. The metal complex formazan dye (21) was demonstrated the significant bactericidal propensity against E. coli, S. aureus, Klebsiella and B. subtilis in solution and on leather by exhibiting maximum ZOIs (19 ± 0.05 mm, 25 ± 0.07 mm, 23 ± 0.09 mm, 27 ± 0.03 mm) and percentage reduction in bacterial growth (60 ± 0.03%, 69 ± 0.07%, 80 ± 0.05% and 86 ± 0.08%) respectively. Hence, newly synthesized formazan dyes (18–23) have efficient optical and antibacterial properties that would be proved valuable for the development of new industrial products to be commercialize.