Three‐dimensional confined self‐assembly (3D‐CSA) of block copolymers (BCPs) is a distinctive and robust strategy that can yield colloidal polymer particles boasting ordered internal structures and diverse morphologies. The unique advantage of neutral interface lies in its ability to create anisotropic particles with surface patterns. The resulting unique polymer particles exhibit deformability under swelling, coupled with excellent spreadability and optical properties. These particles can also be used for fabrication of anisotropic nanoobjects or mesoporous particles via disassembly or serving as templates. This review comprehensively outlines the research advancements in neutral interface‐guided 3D‐CSA systems, including surfactant engineering, internal structure control, properties and future possibilities of anisotropic patterned particles.