The practical implementation of pure lithium nickelate (LiNiO2) as a high-capacity cathode for lithium-ion batteries is obstructed by detrimental H2–H3 phase transitions and cation mixing, which cause significant capacity fading. To address these challenges, we investigated structural and electrochemical properties of LiNiO2 modified by magnesium (Mg) doping and tungsten (W) passivation. Herein, we report that the interplay of 2 mol% Mg doping and 0.5 mol% W passivation successfully mitigates both cation disorder and gliding-induced degradation. The optimized cathode delivers a remarkable capacity retention of 88.1% after 100 cycles at 1 C. The performance enhancement originates from the cooperative mechanism in which Mg doping suppresses Li/Ni cation mixing within the bulk lattice, whereas the W-based surface-passivation-layer alleviates anisotropic strain during cycling. The dual-modification strategy at the both bulk and surface provides a robust pathway to stabilize LiNiO2 and promote its practical implementation in next-generation high-energy lithium-ion batteries.