The CuFe2-xNixO4 (x = 0, 0.1, 0.3, and 0.5) nanoparticles were synthesized using a combustion method and comprehensively characterized to understand their suitability for polymer-based composite applications. X-ray diffraction confirmed the formation of a single-phase spinel ferrite structure with crystallite sizes of 20-30 nm. Energy-dispersive X-ray spectroscopy verified the successful incorporation of Ni ions into the CuFe2O4 lattice, while FE-SEManalysis revealed uniformly dispersed nanoscale particles desirable for composite reinforcement. Optical characterization showed a gradual reduction in band gap energy from 1.81 to 1.75 eV with increasing Ni content, indicating enhanced electronic interactions that can contribute to improved functional performance in polymer matrices. FT-IR spectra further validated the structural stability of the Ni-substituted ferrites through characteristic metal-oxygen stretching vibrations. The tunable structural and optical properties of CuFe2-xNixO4 nanoparticles highlight their potential as promising fillers for multifunctional polymer and hybrid composite materials.