Achieving high-performance polymer semiconductors is a prerequisite for the fabrication of next-generation organic electronics. However, their multi-scale structural ordering remains challenging due to uncontrollable aggregate assembly, thereby limiting the charge carrier mobility. Here we propose a self-templated gradient assembly strategy to controllably modulate multi-scale ordering and alignment of polymers, substantially improving charge carrier mobility. This strategy establishes selection criteria for solvent systems, relying on the coupling framework of solubility parameters and vapour pressures, to trigger supramolecular ordered assembly. Using a newly designed polymer (PFIDTO-BT), we optimize solution-state aggregates and achieve multi-scale structural ordering, alongside visualized tracking of solution-to-solid hierarchical assembly evolution. The precise control yields highly crystalline ordered thin films and single-crystal-like polymer crystals, showing carrier mobility as high as 11.32 and 37.1 cm2 V−1 s−1, respectively, approaching the performance level of polycrystalline silicon. This work provides a generalized paradigm for the rational fabrication of high-performance organic electronic devices.