AbstractThe development of cost‐effective and long‐life rechargeable aluminium ion batteries (AIBs) shows promising prospects for sustainable energy storage applications. Here, we report a heteroatom π‐conjugated polymer featuring synergistic C=O and C=N active centres as a new cathode material in AIBs using a low‐cost AlCl3/urea electrolyte. Density functional theory (DFT) calculations reveal the fused C=N sites in the polymer not only benefit good π‐conjugation but also enhance the redox reactivity of C=O sites, which enables the polymer to accommodate four AlCl2(urea)2+ per repeating unit. By integrating the polymer with carbon nanotubes, the hybrid cathode exhibits a high discharge capacity and a long cycle life (295 mAh g−1 at 0.1 A g−1 and 85 mAh g−1 at 1 A g−1 over 4000 cycles). The achieved specific energy density of 413 Wh kg−1 outperforms most Al–organic batteries reported to date. The synergistic redox‐active sites strategy sheds light on the rational design of organic electrode materials.