Metal oxide nanoparticle (MON) biofunctionalization has a significant impact on biomedical domains. Because of this, it is necessary to comprehend how MON interact with proteins before considering the material for a specific biomedical application. Chemical co-precipitation was used to create ZnO: CuO: Fe₂O₃ nanocomposits. UV spectroscopy, X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and EDAX were used to investigate the synthesised nanocomposites. The single-phase cubic structure was validated by FTIR and XRD. Protein interaction with prepared nanocomposite was carried out using circular dichroism. In addition to the Cu-O and Zn-O vibration modes, the FTIR spectra validate the coexistence of both phases and the distinctive vibration of ferrites atoms at tetrahedral and octahedral sites. Debye Scherrer's formula yielded a crystallite size of 23–28 nm, but SEM revealed that the nanoparticles were 10–30 nm in size. No change in protein conformation on binding with ZnO:CuO:Fe₂O₃ nanocomposites indicates that the BSA-ZnO:CuO:Fe₂O₃ nanocomposite system is biologically compatible. Designing optimised MON for various biomedical applications will benefit from the study.