The ability for silver nanoparticles to function as an antibacterial agent while being separable from the target fluids is important for bacterial inactivation in biological fluids. This report describes the analysis of the antimicrobial activities of silver-coated magnetic nanoparticles synthesized by wet chemical methods. The bacterial inactivation of several types of bacteria was analyzed, including Gram-positive bacteria ( Staphylococcus aureus and Bacillus cereus ) and Gram-negative bacteria ( Pseudomonas aeruginosa , Enterobacter cloacae , and Escherichia coli ). The results have demonstrated the viability of the silver-coated magnetic nanoparticles for achieving effective bacterial inactivation efficiency comparable to and better than that of silver nanoparticles conventionally used. The bacteria inactivation efficiency of our silver-coated MnZn ferrite (MZF@Ag) nanoparticles was also determined for blood platelets samples, demonstrating the potential of utilization in inactivating bacterial growth in platelets prior to transfusion to ensure blood product safety, which also has important implications for enabling the capability of effective separation, delivery, and targeting of the antibacterial agents.