Spinel zinc ferrite (ZnFe₂O₄) nanoparticles have been of high interest owing to their multifunctionality and wide variety of technological and biomedical uses. ZnFe₂O₄ nanoparticles in the current experiment were obtained through the solution combustion technique, which is a simple, quick, and energy-saving method. Zinc and iron metal nitrates were dissolved, and distilled water was used; urea was the fuel used in the combustion process. A solution-combustion reaction occurred upon heating, and an as-burnt powder was formed, which was porous. This was then subjected to calcination to get phase-pure ZnFe₂O₄ nanoparticles. The structural features were analyzed using X-ray diffraction, whereby it was found that the material formed a single-phase cubic spinel structure, which was of good crystalline nature. The average crystallite sizes were calculated as 34.9 nm for pure ZnFe₂O₄ and 15.08 nm for the doped sample, indicating a nanocrystalline nature. UV-Visible spectroscopy confirmed the semiconducting nature of the synthesized samples, with direct optical band gap values increasing from 2.14 eV for pure ZnFe₂O₄ to 2.25 eV for the Ni-doped ZnFe₂O₄ sample. The synthesized ZnFe₂O₄ nanoparticles are promising materials to be used in Structural, morphological, and optical applications due to the combined structural stability along with a tunable optical band gap.