Spinel ferrite Co1e2xNixMnxFe2eyCeyO4 (0.0 x ¼ y 0.3) nanoparticles (NPs) were prepared by sol-gel auto-combustion method. The synthesized NPs were examined using several techniques such as X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) coupled with EDX and elemental mapping, transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), and a vibrating sample magnetometer (VSM). The analysis of the crystal structure and the phase identification of samples indicates the formation of spinel cubic phase with the occurrence of CeO2 as secondary phase when the content of Ce substitution element increases. In addition, all produced samples exhibit cubic symmetry with space group Fd3m. TEM confirms the presence of two phases, i.e., the cubic spinel ferrite and the cubic cerium oxide (CeO2). The characteristics of hysteresis loops reveal the soft ferrimagnetic nature of the different synthesized samples. The saturation (Ms) and remanent (Mr) magnetizations fall on increasing the content of substituting elements. Compared with pure CoFe2O4 NPs, the value of coercive field (Hc) slightly increases for x ¼ y ¼ 0.1 and x ¼ y ¼ 0.2 NPs. Then, Hc reduces with further increasing the x and y contents. The squareness ratio is found to be in the 0.528e0.400 interval, indicating the single domain NPs with uniaxial anisotropy for the different produced NPs. The magneto crystalline anisotropy constant (Keff), anisotropy field (Ha), magneton number (nB) and the demagnetizing field (N) were also determined and discussed.