This work investigated the effect of dysprosium (Dy) ions on the structural, microstructural and magnetic properties of nickel nanospinelferrite, NiFe2O4. The nanoparticles (NPs) of NiDyxFe2–xO4 (0.0 ≤ x ≤ 0.1) were prepared via the hydrothermal method. The formation of cubic phase of Ni nanoferrite was confirmed through X-ray diffraction, field emission scanning and transmission electron microscopy. Moreover, the magnetic properties of NiDyxFe2–xO4 (0.01 ≤ x ≤ 0.10) NPs were discussed. The magnetization versus field, M(H) curves exhibit super paramagnetic nature at room temperature and ferrimagnetic nature at low temperature (10 K). A noticeable improvement in the different deduced magnetic parameters is obtained especially for the NiDy0.07Fe1.93O4(x = 0.07) product. The obtained result is mostly derived from the substitution of Fe3+ ions of smaller ionic radii with Dy3+ ions of larger ionic radii that will strengthen the super exchange interactions among nanoparticles. The calculated squareness ratios are found to be much less than 0.5, due to the effect of spin disorder in the surface regions of NiDyxFe2–xO4 (0.01 ≤ x ≤ 0.10) NPs. The Dy3+ ions substitution increases the magnetic hardness (higher values of remanence Mr, coercivity Hc, and magnetic moment nB) of nickel nanoferrite samples. In this paper, we examined the influence of dysprosium (Dy) on the structural, microstructural and magnetic properties of nickel nano spinel ferrite synthesized via the hydrothermal method. The magnetization versus field, M(H) curves exhibit superparamagnetic nature at room temperature and ferrimagnetic nature at low temperature (10 K). A noticeable improvement in the different deduced magnetic parameters is obtained especially for the NiDy0.07Fe1.93O4 (x = 0.07) product. Display omitted