<p>Using the sol–gel auto-combustion process, the nanocrystalline Zn_0.2Co_0.2Ni_0.6Fe₂O₄ was created with the focus on analyzing the effect of calcination temperature on its structural and magnetic properties, specifically cation redistribution. The formation of the cubic spinel structure was verified by X-ray diffraction. As the calcination temperature increased from 400 to 600 °C, the crystallite size grew from 38.384 to 49.776 nm. Zn²⁺ ions were found to mainly occupy tetrahedral (A) sites according to Rietveld analysis, but Ni²⁺, Co²⁺, and Fe³⁺ ions were distributed over both A and B sites, suggesting a mixed spinel structure. The values of experimental and theoretical lattice parameters were very close to each other, confirming the successful cation distribution into their corresponding lattice sites. Two primary absorption bands were found by Fourier-transform infrared spectroscopy: a high-frequency absorption band (<i>ν</i>₂) at around 560.367 and 569.323 cm⁻¹ and a low-frequency absorption band (<i>ν</i>₁) between 375.936 and 383.264 cm⁻¹. The bands correspond to metal–oxygen stretching vibrations at tetrahedral and octahedral sites, confirming the spinel structure and accurate cation-site distribution. Depending on the calcination temperature, field emission scanning electron microscopy showed that most particles were spherical, with some agglomeration. Magnetic measurements at ambient temperature using a vibrating sample magnetometer showed that saturation magnetization decreased from 57.972 to 56.096 emu/g with increasing temperature. The nanoferrites exhibited soft magnetic behavior at room temperature, indicating potential for high-frequency and microwave applications, with coercive field values ranging from 325.284 to 364.915 Oe, typical of soft magnetic materials.</p>