Spinel ferrite Ni0.08Mn0.90Zn0.02Fe₂O₄ was prepared by a conventional ceramic process followed by sintering at three different temperatures (1050∘ C, 1100∘ C and 1150∘ C). X-ray diffraction (XRD) investigations stated the single-phase cubic spinel structure and the FTIR spectra revealed two prominent bands within the wavenumber region from 600 cm−1 to 400 cm−1. Surface morphology showed highly crystalline grain development with sizes ranging from 0.27 μm to 0.88 μm. The magnetic hysteresis curve at ambient temperature revealed a significant effect of sintering temperature on both coercivity (Hc) and saturation magnetization (Ms). Temperature caused a decrease in DC electrical resistivity, while the electron transport increased, suggesting the semiconducting nature of all samples and that they well followed the Arrhenius law from which their activation energies were determined. The values of Curie temperature (Tc) and activation energy were influenced by the sintering temperature. Frequency-dependent dielectric behavior (100 Hz–1 MHz) was also analyzed, which may be interpreted by the Maxwell–Wagner-type polarization. The UV–vis–NIR reflectance curve was analyzed to calculate the bandgap of ferrites, which showed a decreasing trend with increasing sintering temperature.Spinel ferrite Ni0.08Mn0.90Zn0.02Fe₂O₄ was prepared by a conventional ceramic process followed by sintering at three different temperatures (1050∘ C, 1100∘ C and 1150∘ C). X-ray diffraction (XRD) investigations stated the single-phase cubic spinel structure and the FTIR spectra revealed two prominent bands within the wavenumber region from 600 cm−1 to 400 cm−1. Surface morphology showed highly crystalline grain development with sizes ranging from 0.27 μm to 0.88 μm. The magnetic hysteresis curve at ambient temperature revealed a significant effect of sintering temperature on both coercivity (Hc) and saturation magnetization (Ms). Temperature caused a decrease in DC electrical resistivity, while the electron transport increased, suggesting the semiconducting nature of all samples and that they well followed the Arrhenius law from which their activation energies were determined. The values of Curie temperature (Tc) and activation energy were influenced by the sintering temperature. Frequency-dependent dielectric behavior (100 Hz–1 MHz) was also analyzed, which may be interpreted by the Maxwell–Wagner-type polarization. The UV–vis–NIR reflectance curve was analyzed to calculate the bandgap of ferrites, which showed a decreasing trend with increasing sintering temperature.