Nanoparticles of Co0.6Zn0.4Fe2O4, with narrow size distribution, regular morphology, and high saturation magnetization, have been synthesized. The synthesis, involved a very rapid mixing of reducible metal cations with sodium borohydride, is carried out in a colloid mill and followed by a separate hydrothermal process. The microstructure and magnetic properties of the synthesized nanoparticles are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM). The effects of different synthesis conditions (synthesis temperature and reaction time) on the characteristics of the ferrite nanoparticles are discussed. The changes in cation contribution are revealed by the Raman study. The magnetic measurements explore that all the as-synthesized samples are superparamagnetic in nature. The corresponding superparamagnetic behavior is explained by paramagnetic Langevin theory. Note that, the superparamagnetic Co0.6Zn0.4Fe2O4 ferrite nanoparticle, with excellent performance, can be synthesized at 160°C for a short reaction time (4 h).