A series of nickel doped zinc ferrite NixZn1-xFe2O4 (0 ≤ x ≤ 0.6) nanoparticles were prepared using sol-gel method. The influence of Ni2+ ions content on the lattice parameter, particles size, line width and the magnetization of specimens were subsequently studied. The XRD patterns infer the single phase formation of synthesized nanoparticles. The lattice parameter decreases linearly from 8.368 Å to 8.264 Å, whereas crystallite size increases with nickel concentration. The variation in crystallite size is also in correlation with the particle size observed through HRTEM. Further, the saturation magnetization increases from 26.70 emu/gm for x = 0.0 to 45.85 emu/gm for x = 0.4 with the increase in nickel content. The increase in saturation magnetisation is also supported by spin concentration as calculated from EPR study.