A series of Ni_1-xCu_xFe₂O₄ (0.0 ≤ x ≤ 1.0) nanofibers have been synthesized employing electrospinning method at 650°C. The effect of Cu substitution on structural, morphology and magnetic properties of NiFe₂O₄ nanofibers is reported. The XRD analysis showed the formation of single-phase cubic spinel Ni-Cu ferrite and an increasing behavior of lattice constant. The surface morphology is characterized by SEM, it is investigated that nanofibers have uniform and continuous morphology. The VSM results showed Cu substitution played an important role in magnetic properties of Ni_1-xCu_xFe₂O₄. The saturation magnetization (M_s) decreases linearly with increasing Cu²⁺ content, while coercivity (H_c) has slowly decreased before x ≤ 0.5, and then sharply increased to 723.9 Oe for x = 1.0. The magnetic properties of Ni_1-xCu_xFe₂O₄ can be explained in Neel’s model, cation distribution and shape anisotropy.