Due to the uniqueness and the variation of the ionic radius and oxidation states of the implanted transition metals within nano ferrites structure, The nano ferrites are integrated into many technologies including biomedical application the current study aims to optimize the effect of cerium-dopant on the magnetic behavior and antimicrobial properties of manganese nano ferrites. Cerium-doped manganese nano ferrites are synthesized by chemical co-precipitation method followed by thermal annealing at 500 °C. and investigate the dopant effects on its magnetic behavior and antibacterial properties for biomedical applications. The cubic spinel ferrite is successfully formed and CeO₂ and Fe₂O₃ have appeared as minor phases. The particle size is found to be 20–60 nm. The Ce_0.05Mn_0.95Fe₂O₄ nano ferrite exhibits the highest saturation magnetization of about 20.47 emu/g with 118.22 Oe as coercivity. EPR factors were affected due to crystalline anisotropy that appeared inside the Ce_xMn_X-1Fe₂O₄ spinel ferrites nanomaterials. In comparison to chloramphenicol, cerium nanoparticles exhibited promising inhibitory action against six pathogenic bacteria (Bacillus cereus, Bacillus subtilis, Micrococcus luteus, Escherichia coli, Klebsiella pneumoniae, and Serratia plymuthica). All cerium treatments showed suitable antibacterial activities. However, the treatments of X = 0.000, X = 0.025, and X = 0.050 were the most effective. For Gram-negative bacteria, the best treatment was X = 0.025, while for Gram-positive isolates, the best treatment was X = 0.050 with MIC 5–10 µg/ml. Our finding, open the pathway to integrate cerium doped manganese nano ferrites in biomedical application including against human pathogenic bacteria.