The present study focuses on the investigation of magnetic and temperature-dependent dielectric properties of Co-CuFe 2 O 4 nanoferrites. CuFe 2 O 4 , Cu 0.5 Co 0.5 Fe 2 O 4 and CoFe 2 O 4 nanoparticles were prepared using sol–gel auto-combustion. X-ray diffraction (XRD) pattern shows a phase transformation from tetragonal (for CuFe 2 O 4 ) to cubic (for Cu 0.5 Co 0.5 Fe 2 O 4 and CoFe 2 O 4 ) structure. Surface morphology of synthesized samples was analyzed by scanning electron microscopy, which shows formation of agglomerated, irregular shaped nanoparticles. Fourier transform infrared and Raman spectra of CuFe 2 O 4 , Cu 0.5 Co 0.5 Fe 2 O 4 and CoFe 2 O 4 nanoparticles support the results of XRD analysis. The UV–visible spectra of all the samples show strong absorption maxima in the visible range and are used to calculate the energy band gap of the synthesized nanoferrites. It was noticed that the value of band gap is highest for CuFe 2 O 4 (1.58 ± 0.02 eV) nanoparticles in comparison to Cu 0.5 Co 0.5 Fe 2 O 4 (1.18 ± 0.02 eV) and CoFe 2 O 4 (1.01 ± 0.02 eV) ferrite systems. Magnetic study shows the highest value of coercivity (H c ) and squareness ratio ( S ) for Cu 0.5 Co 0.5 Fe 2 O 4 ( H c  = 959.10 ± 0.30 Oe, and S  = 0.45 ± 0.05) ferrite. The dielectric measurement revealed a significantly lower value of tangent loss (tan δ ) at higher frequencies for Cu 0.5 Co 0.5 Fe 2 O 4 and CoFe 2 O 4 ferrite samples in comparison to that for CuFe 2 O 4 . The high value of magnetic parameters, high resistivity (~ 10 7 –10 8 Ω cm), and low dielectric loss at high frequencies for Cu 0.5 Co 0.5 Fe 2 O 4 and CoFe 2 O 4 nanoferrites suggests that the materials are potential candidate for high density magnetic recording media and also to be used in power transformers at high frequencies.