Comb-shaped poly(arylene ether sulfone)s with pendant alkyl imidazolium groups were developed as anion-exchange membranes (AEMs). The imidazolium-functionalized polymers with relatively long alkyl chains formed self-aggregated structures with large ionic clusters and clear hydrophilic–hydrophobic phase separation. These comb-shaped membranes, with ion-exchange capacities of only 0.92–1.14 meq g⁻¹, showed very high hydroxide conductivities of over 0.03 S cm⁻¹ at 20 °C and 0.14 S cm⁻¹ at 80 °C. Furthermore, the self-aggregated structure resulting from these comb-shaped polymers exhibited excellent thermal, mechanical and dimensional stability, as well as superior chemical stability at high pH.