Achieving high energy densities in lithium-ion batteries requires advancements in electrode materials and design. This study investigated the incorporation of multi-walled carbon nanotubes (MWCNTs) with high commercial viability as conductive additives into two types of high-nickel cathode materials, LiNi_0.8Co_0.1Mn_0.1O₂ and LiNi_0.92Co_0.07Mn_0.01O₂. To ensure a uniform distribution within the electrodes, MWCNTs were uniformly dispersed in the solvent using ultrasonication, the most effective and straightforward dispersion method. This enhancement improved both electronic and ionic conductivity, facilitating the formation of an efficient electron transfer network. Unlike the cells using only carbon black, the electrodes with MWCNTs exhibited lower internal resistances, facilitating higher lithium-ion diffusion. The cells with MWCNTs exhibited a capacity retention of 89.5% over their cycle life, and the cells with 2 wt% MWCNTs exhibited a superior rate capability at a high current density of 1 C. This study highlights that incorporating well-dispersed MWCNTs effectively enhances the electrochemical performance of ultrahigh-loading cathodes in lithium-ion batteries (LIBs), providing valuable insights into electrode design.