The construction of precise soft matter nanostructures in solution presents a challenge. A key focus remains on the rational design of func-tionalities to achieve the high morphological complexity typically found in biological systems. Advances in controlled polymerisations and self-assembly increasingly allow approaches towards complex hierarchical nanomaterials. By combining tailor-made cylindrical polymer brushes, block copolymers and interpolyelectrolyte complexation-driven self-assembly, we demonstrate a facile construction of uniformly compartmentalised and topographically structured polymeric nanowires in aqueous media. The approach offers a modular avenue in pro-gramming the internal morphology of polymer nanowires by varying the block copolymer composition and topology.