Ni-rich cathodes are very attractive in terms of high-energy density cathodes. However, it still suffers from various disadvantages, making commercialization more difficult. A dual-modifying cathode is a simple and efficient strategy that can have a synergistic effect of surface coating on the outside, and doping can have internal structure stabilization. CSTR-level doping of Mg2+ can significantly extend the battery’s cycle life due to its pillar effect, and LiNbO3 is a prominent coating material with high ionic conductivity. The dual-modified cathode in this study has shown excellent electrochemical performance in terms of cyclic stability and rate performance, even at 4.5 V vs. Li. The modified cathode showed 85.4% capacity retention at 4.3 V and 87.11% at 4.5 V, whereas the bare showed only 78.9% and 68.2%, respectively. The LiNbO3-coating protects the material from the surface side reactions from the electrolytes at high voltage operations, and the “pillar effect” due to Mg2+ doping stabilizes the structure for longer cycles and higher C-rates, making this dually modified cathode a prominent cathode material for lithium-ion batteries. Graphical abstract: (Figure presented.)