MgFe2O4 and MgFe2O4/(1−x)MnO–xCdO (x = 0.0, 0.1, 0.3, 0.5, and 0.7) samples were synthesized using a co-precipitation procedure. The structural and microstructural parameters of the phases formed and their percentages were explored applying X-ray diffraction (XRD). Only two phases were detected MgFe2O4 (MFO) and CdO, while Mn ions was incorporated into the MFO phase. Analysis revealed cation redistribution in MFO lattice due to incorporation of Mn and some Cd ions causing increasing the cell constant (8.385 → 8.419 Å). Fourier transform infrared (FTIR) confirmed cation redistribution. XRD Rietveld analysis and TEM imaging disclosed different particle size for MFO and CdO and a little variation with (x); MFO (10–13 nm) and CdO (45–49 nm). Samples morphology and chemical composition were examined by SEM and EDS analysis. The values of the optical band gaps obtained for MFO and MFO/(1−x)MnO–xCdO are 1.91, 1.63, 1.7, 1.55, 1.65, and 1.71 eV for samples x = 0, 0.1, 0.3, 0.5, and 0.7, respectively. The influence of the composition parameter (x) on the absorbance, extinction coefficient, refractive index, dielectric constant, optical conductivity, and non-linear optical parameters performance was investigated. All samples exhibited a weak ferrimagnetic nature with enhancement in saturation magnetization. The saturation magnetization increased (14.6 → 21.8 emu/g) and coercivity decreased (21 → 6 Oe) but non-monotonically with the content of CdO relative to MnO.