Mixed manganese‒neodymium‒copper (Mn–Nd–Cu) nanoferrites were synthesized using the sonochemical method. The X-ray diffraction (XRD) pattern showed a cubic spinel structure and lattice parameters were determined from the XRD spectra. Fourier transform infrared spectra were used to characterize the chemical bond of tetrahedral and octahedral sites in the spinel ferrites. The surface morphology and elemental composition were analyzed by scanning electron microscopes coupled with energy-dispersive X-ray spectroscopy, which showed spherical elongated agglomeration with desired elemental peak. The optical bandgap energies increased with the inclusion of Nd 3+ , which was investigated using the UV-diffuse reflectance spectrum. The dielectric parameter decreased with an increase in frequency. The relatively low AC conductivity values were obtained for the Mn–Nd–Cu nanoferrites. The magnetic hysteresis curve showed that low coercivity indicates that the prepared nanoferrites had a soft magnetic material with ferromagnetic nature. The enhanced optical bandgap, decreased dielectric loss, and low coercivity of NMC4 indicated that the prepared nanoferrites could be used in electronic devices at a super high frequency. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.