Rechargeable aqueous Zn batteries (RAZBs) offer a promising solution for safe and cost-effective energy storage. However, practical applications of this type of battery are hindered by dendrite formation and side reactions, which primarily stem from the unstable Zn electrode-electrolyte interface (EEI). Here, we report 3-(1-pyridinio)-1-propanesulfonate (PPS) as a novel EEI regulator to tackle these critical issues. Theoretical calculations and experimental results reveal that PPS molecules can be preferentially adsorbed on the Zn anode surface and construct a lean-water EEI, which regulates uniform Zn plating/stripping and minimizes interfacial side reactions. As a result, the addition of PPS enables a Zn//Cu asymmetric cell to achieve an ultra-high Coulombic efficiency of 99.88% and a lifespan of over 4,000 cycles (around half a year), far exceeding that with a conventional electrolyte (99.65% and 210 cycles). Remarkably, even at 20 mA cm−2 and a high depth of discharge of 70%, the Zn//Zn battery using the new electrolyte can still maintain an impressive cycling life of over 250 h. More importantly, the implementation of the designed electrolyte in various Zn-based full cells yields exceptional capacity retention and lifespan. This work underscores the importance of EEI regulation in advancing RAZB technology and offers a simple yet effective strategy for enhancing the stability and reversibility of Zn anodes, which represents a key step toward realizing the full potential of RAZBs for next-generation energy storage.