•CoFe2-CoFe2O4 were synthesized using NaBH4 reduction process in a chitosan solution.•Chemical crosslinking favored the formation of CoFe2O4 in the synthesis process.•The average size of the nanoparticles obtained varied within a range of 4–13nm.•Ferromagnetism, spin glass and exchange-spring were observed in the nanocomposites. Magnetic nanocomposites of CoFe2-CoFe2O4 were synthesized using the borohydride reduction process in a chitosan solution of FeCl2·4H2O and CoCl2·6H2O. The chemical crosslinking favored the formation of cobalt ferrite in the nanoparticle synthesis process. The phase structure, particle size, morphology and magnetization of the nanoparticles were investigated by X-ray diffraction (XRD), Mössbauer spectroscopy (MS), scanning electron microscopy, and vibrating sample magnetoscopy, respectively. The XRD results showed that the samples are mostly made up of amorphous phases and MS shows that the phases are Fe-B. The average size of the nanoparticles obtained varied within a range of 4–13nm. Different magnetic behavior such as ferromagnetism, spin glass and exchange-spring were observed in the nanocomposites depending on the quantify of CoFe2O4.