NixCu0.2ZnyFe1.98O4 (x = 0.16, 0.26, 0.35, 0.43, 0.50; y = 0.8−x) ferrites were prepared via solid-state reaction. The influence of Ni2+ concentration on ferrites composition, microstructure, magnetic properties and DC-bias superposition characteristics was studied by XRD, SEM, XPS, and VSM. Then, the effect of magnetic properties on the DC-bias superposition characteristics was analyzed. The results showed that the ferrites sintered at 900 °C for 3 h were all in pure spinel phase with an average grain size of 7.5 μm and a relative density of about 5.15 g cm−3. With the increase in Ni2+ concentration, the saturation magnetization (Ms) and coercivity (Hc) of ferrites increased, but the magnetocrystalline anisotropy constant (K1) first increased and then decreased. And the Ms, Hc, and K1 of the specimen with x = 0.43 were 63.62 emu·g−1, 27.36 Oe, and 1813.17 Oe·emu·g−1, respectively. In particular, the specimen of x = 0.50 achieved the best DC superposition characteristics, where the H70% was about 220 A m−1. The incremental permeability of the specimens decreased rapidly at a bias magnetic field <400 A m−1. The variation mainly originated from the domain wall displacement, and the rate of decrease was influenced by both Ms and K1. At a bias magnetic field ≥400 A m−1, the incremental permeability of the specimens decreased slowly, mainly because the number of domain walls decreased until disappearing, and the specimens tended to become a single domain structure. And the rate of decrease of incremental permeability was mainly affected by K1.