Objectives: Nanoparticles of CoFe2–xEuxO4 (x = 0, 0.025, 0.05, 0.075, and 0.1) were successfully synthesized by simple coprecipitation method. Experimental: Field emission scanning electron microscopy (FE-SEM) images revealed europium-doped cobalt spinel ferrite nanoparticles formed after calcination of the precursor at 900 °C for 1 h, with sizes of approximately 20–40 nm. Energy dispersive X-ray spectra (EDXS) confirmed the presence of Co, Fe, Eu, and O elements with no evident of impurities. Results calculated from powder X-ray diffraction (PXRD) data show that the average crystallite size and lattice parameters decrease with increasing europium content. Conclusions: The doping of Eu3+ ions in the cobalt ferrite structure affects the optical and magnetic properties of the substrate material. In this case, the values of band gap energy (Eg), coercivity (Hc) and remanent magnetization (Mr) increase with increasing concentration of Eu3+ ion, while optical absorption and saturation magnetization exhibit an opposite trend. The excellent optical and magnetic properties of un-doped and Eu-doped CoFe2O4 nanoparticles suggest great potential for applications related to optics and magnetism.