In this work, we present a facile strategy to significantly enhance the aggregate emission of PDI based on polymerizationmediated TSCT. Using functionalized PDIs with initiating sites on the imide group, donor monomers with weak to strong electron-donating ability were (co)polymerized via ATRP. It is revealed that the strong emission of the obtained PDI polymers results from distorted PDI π-π stacking, which is influenced simultaneously by the steric effect from the polymeric units and the TSCT interaction between the donor groups and the PDI scaffold. Both linear and four-arm polymers showed effective emission enhancement, whereas the latter showed a much stronger effect.