Biofilm formation on medical devices can cause persistent infections. The main feature of biofilms is their self-produced extracellular polymeric substances (EPS) that act as a protective shield to prevent biocide penetration. Iron oxide magnetic nanoparticles (MNPs), synthesized through a simple process, were used as “shield breakers” to damage the biofilm matrix and cause biofilm detachment. The Methicillin-resistant Staphylococcus aureus (MRSA) strain was used to demonstrate the efficacy of MNPs. The highest logarithmic reduction (4.71 log) of S. aureus biofilm was achieved after treatment with 30 mg/mL of 11 nm MNPs under rotating magnetic field for 15 minutes. MNPs caused strong mechanical disruption to the matrix and led to biofilm dispersal. Both alternating and rotating magnetic fields improved the effect of MNPs on biofilm damage. The increased MNPs solution temperature produces by hyperthermic effect in the AC field while the MNPs caused physical damage on biofilms in rotating magnetic field.