Water contamination by organic dyes and pathogenic bacteria has a negative impact on human health. Bimetallic nanoparticles are promising materials in water treatment. In the current study, a bimetallic of copper and iron nanoparticles (CuO/Fe2O3 NPs) was synthesized by the extract of Fusarium oxysporum. CuO/Fe2O3 NPs were characterized using different methods such as UV–Vis spectroscopy and transmission electron microscopy (TEM). The micrographs of TEM showed particle sizes ranging from 4-12 nm while UV–Vis analysis exposed the characteristic peak at 277 nm after the synthesis of CuO/Fe2O3 NPs. The antimicrobial activity of CuO/Fe2O3 NPs was tested against Gram +ve (Streptococcus sp, Bacillus subtitles), and Gram -ve (E. coli, Salmonella typhi) bacteria. The biosorption of Congo Red (CR) dye using the bio-synthesized CuO/Fe2O3 NPs was studied. The biosorption studies were investigated at different time intervals and different dye concentrations. The studies revealed that the bio-sorption percentage of 97.167 % was achieved only after 10 min of contact at 25 ppm. The maximum Langmuir isotherm adsorption capacity was 155.738 mg/g. For the kinetic studies, the bio-sorption process followed the pseudo-second-order model and it was involved in more than one single kinetic stage.