Aerobic digestion is widely used to stabilize and reduce waste activated sludge in the decentralized wastewater treatment plants, but it would deteriorate sludge dewaterability. Thus, improving the dewaterability of aerobically digested sludge (AeDS) is of vital significance for sludge disposal and management. This study investigated the possibility of zero-valent iron (ZVI)/sulfite system for promoting the dewaterability enhancement of AeDS. The results showed that ZVI/sulfite system was favorable to improve the dewaterability of AeDS. The highest reduction of capillary suction time and the lowest value of water content of sludge cake were (81.7 ± 3.6)% and (69.3 ± 1.2)%, respectively, under the optimal experimental conditions (reaction time = 60 min, ZVI = 0.9 mmol/g volatile solids (VS), sulfite = 1.2 mmol/g VS, pH = 6, and purging air). Compared to Fe²⁺/sulfite and Fe³⁺/sulfite systems, ZVI/sulfite system was more favorable to improve the dewatering performance of AeDS. The results also demonstrated that the main radical species in ZVI/sulfite system were sulfate radical and hydroxyl radical, which could effectively degrade tightly-bound extracellular polymeric substances and then led to the release of bound water and the increase of zeta potential. Consequently, the dewatering performance of AeDS was obviously enhanced. Additionally, the reusability of recovered ZVI in ZVI/sulfite system for AeDS conditioning was satisfactory.