Nanostructured supramolecular polymers (SPs) are filamentous assemblies possessing a high degree of internal order and have important uses in regenerative medicine, drug delivery, and soft matter electronics. Despite recent advances in functional SPs, a challenging topic is the development of robust assembly protocols enabling the incorporation of various functional units without altering its supramolecular architecture. We report here the robust tubular assembly of camptothecin (CPT) analogues into functional SPs. Covalent linkage of two CPT moieties to various short hydrophilic segments (e.g., nonionic, cationic, anionic, and zwitterionic) leads to a class of CPT analogues that self-assemble in water into tubular SPs. Systemic administration of nonionic SPs effectively suppresses tumor growth. Furthermore, these tubular SPs act as universal dispersing agents in water for low-molecular-weight hydrophobes.