In this paper, synthesis of Ni _0.5 Zn _0.5 Fe ₂ O ₄ nanoparticles via sol-gel process followed by fabrication of ultra-thin layer (90 μm) of ferrite-polymer nanocomposite on an aluminum (Al) substrate is carried out. The structural characterizations show that pure Ni-Zn ferrite phase formation occurred with average particles size of ~ 19 nm. The nanocomposite coating shows excellent broadband absorption properties over the frequency range 4-15 GHz with absorptivity of greater than 85%. Simulations were performed for obtaining the optimum film-thickness of ferrite-nanocomposite and found that the return loss for varying thickness of ferrite layer was minimum for 5 μm thickness.