A simple method for the preparation of magnetic nanocomposites consisting of NiFe2O4 nanoparticles, polybenzoxazine (PB), linear low-density polyethylene (LLDPE) and LLDPE-g- Maleic anhydride (LgM) is described. Composites were prepared by forming benzoxazine- NiFe2O4 nanocomposites followed by melt blending with LLDPE and thermal curing of benzoxazine. The composites were characterized by XRD, DSC and TGA, FT-IR, SEM, UTM and VSM. The saturation magnetization of the composites containing 33.25 wt% NiFe2O4 was 7.72 emu/g and it decreased with decreasing amount of NiFe2O4 in the composite. The composite films exhibited mechanical flexibility as well as magnetic properties. © 2013 Copyright Taylor and Francis Group, LLC.