CoFe₂O₄ nanoparticles, synthesized via a co-precipitation method at 120 °C, exhibited excellent microwave absorption properties, with minimum reflection loss of −55 dB (∼99.99%) at 9.25 GHz. To the best of our knowledge, these synthesized CoFe₂O₄ nanoparticles show the highest minimum reflection loss in comparison with the reported CoFe₂O₄ based materials.