<p>During precision machining of bearing inner walls, high-hardness bearing steel often suffers from high cutting force, elevated cutting temperature, severe tool wear, and unstable machined surface quality. These problems seriously restrict the efficient machining of high-hardness bearing steel components. To address these issues, a polycrystalline cubic boron nitride (PCBN) bionic tool for bearing inner wall machining was designed and fabricated based on bionic principles. The geometric features of the inner contour of limpet teeth were extracted through biological dissection and microscopic observation. The variable-curvature configuration was then parametrically modeled and introduced into the rake face of the PCBN tool, forming a PCBN tool structure with a bionic variable-curvature chip-breaking groove. Finite element simulation was used to analyze the effects of different structural parameters on cutting force, cutting temperature, Mises stress, and strain distribution. The optimized bionic structural parameters were obtained, and the corresponding PCBN bionic tool was fabricated. Comparative cutting experiments were then conducted between the PCBN bionic tool and a conventional PCBN tool, with cutting force, cutting vibration, and tool wear as the main evaluation indexes. The results show that, compared with the conventional PCBN tool, the PCBN bionic tool reduced the cutting force by up to 23.71% and the vibration acceleration in the main cutting-force direction by up to 55%. It also improved the machined surface roughness and reduced tool wear. These results indicate a significant improvement in cutting performance. This paper provides a new approach for the structural innovation of cutting tools used in high-strength steel machining.</p>