A one-step overall strategy from surface to bulk was proposed to simultaneously synthesize the Nb-doped and LiNbO₃-coated LiNi_0.83Co_0.12Mn_0.05O₂ cathode materials. The incorporation of LiNbO₃ coating can regulate the interface and facilitate the diffusion of Li-ions. Simultaneously, the stronger Nb—O bond can effectively suppress Li⁺/Ni²⁺ cation mixing and strengthen the stability of crystal structure, which helps to mitigate the anisotropic variations of lattice parameters during Li⁺ de/intercalation. The results showed that the dual-modified materials exhibited good structural stability and distinguished electrochemical performance. The optimal NCM-Nb2 sample showed an excellent capacity retention of 90.78% after 100 cycles at 1C rate between 2.7 and 4.3 V, while only 67.90% for the pristine one. Meanwhile, it displayed a superior rate capability of 149.1 mA·h/g at the 10C rate. These results highlight the feasibility of one-step dual modification strategy to synchronously improve the electrochemical performance of Ni-rich layered oxide cathodes.