Abstract Rechargeable aqueous zinc‐ion batteries (ZIBs) are expected to be the next generation of low‐cost, safe, and high‐energy‐density energy storage systems. However, undesirable electrode/electrolyte interfacial (EEI) side reactions of anode and dissolution of cathode materials during cycling of ZIBs have led to drastic degradation of battery performance. Here, a phosphated electrolyte is developed to facilitate the simultaneous formation of a Zn 3 (PO 4 ) 2 ‐rich solid electrolyte interphase (SEI) and the cathode/electrolyte interface (CEI) as well as improved solvent chemistry. The in situ generated robust EEI induce uniform deposition of zinc and inhibit solvation of the cathode material to achieve a high performance ZIBs. The improved solvent chemistry promises stable cycling at low temperatures with an ultra‐long life of 600 h at −10 °C. Moreover, the pouch cell with phosphated electrolyte exhibits excellent cycling performance with no significant capacity degradation after 150 cycles. In addition, the phosphated electrolyte in anode‐free ZIBs performances a long lifetime of 200 cycles. This study provides a simple and effective strategy for interface construction in ZIBs.