In this study, a novel immobilizing carrier with α-Fe2O3 magnetic nanoparticles was developed and used for immobilization of atrazine-degrading bacterial isolates of Bacillus spp. Since the free cells of microorganisms generally not succeed to degrade pollutants; thus, extra treatments are alluring to make strides biodegradation. Scanning electron microscope (SEM) images appeared that after immobilization the bacterial cells were totally retained and entirely distributed on the surface of α-Fe2O3 magnetic nanoparticles. The performance of α-Fe2O3 immobilized cells in atrazine (ATZ) degradation was compared with the free cells, which was about 90.56% in 20 days. Experimental results exhibited that ATZ could be degraded at a broad range of physicochemical parameters viz. pH (4.0 to 9.0), temperature (20 to 45 °C), ATZ concentration (50 to 300 mg L−1) and agitation speed (50 to 300 rpm), which underlines that α-Fe2O3 immobilized cells could tolerate a higher range of ATZ concentration as compared to free cells. This research demonstrated that α-Fe2O3 could be applied as a potential carrier in cell immobilization and biodegradation of ATZ herbicide with greater efficiency.