Potential of indigenous biofilm forming Staphylococcus and Bacillus sp. to decolorize and transform Mordant Black 11 dye was exploited for the reclamation of contaminated environmental compartments. The dye decolorization potential of the bacterial strains was assessed against variable environmental parameters. Both the strains exhibited > 50% decolorization of dye in the absence as well as presence of carbon source over 72 h. Bacillus subtilis MB378 was the most potential and efficient strain which exhibited 75.23% decolorization of Mordant Black 11 dye at 37 ˚C within 48 h in glucose supplemented medium. Optimum decolorization of Mordant Black 11 dye by Bacillus subtilis MB378 under aerobic conditions was attained at pH 8 and 30 ˚C within 24 h of incubation. The bacterial strain also possessed the ability to tolerate high concentrations of Mordant Black 11 dye up to 150 mg L−1. Quantitative assessment revealed maximum decolorization of Mordant Black 11 dye (76.12%) by Staphylococcus sp. MB377 at acidic pH, 37 ˚C with 1% inoculum size. Mordant Black 11 dye on addition of metals followed the dye decolorization order as Cd > Cu > Cr. IR analysis, UV–vis spectroscopy, HPLC and GCMS profiles ascertained the biodecolorization and biotransformation potential of these strains supporting effective utilization of indigenous biofilm forming bacteria for comprehensive treatment of dye containing effluents.