This study introduces phenylalanine (Phe) as a multifunctional additive to improve the reversibility of the Zn anode in aqueous Zn²⁺-ion batteries (AZIBs). Phe, a ubiquitous biomolecule, exhibits nucleophilic characteristics that coordinate with Zn²⁺ ions, optimizing the solvation environment. Its lipophilicity enables higher adsorption energy, forming a protective interphase. The hydrophobic benzene ring ligands repel H₂O molecules, while the hydrophilic groups attract Zn²⁺ ions, homogenizing their flux. The preferential reduction of Phe before H₂O facilitates the in situ formation of an organic-inorganic hybrid solid electrolyte interphase (SEI), enhancing interfacial stability. This results in improved electrochemical performance, with ZnIIZn cells achieving an extended cycle life of 5250 hours and ZnIILOMO cells retaining 77.3% capacity after 300 cycles, demonstrating significant potential for commercialization.This study introduces phenylalanine (Phe) as a multifunctional additive to improve the reversibility of the Zn anode in aqueous Zn²⁺-ion batteries (AZIBs). Phe, a ubiquitous biomolecule, exhibits nucleophilic characteristics that coordinate with Zn²⁺ ions, optimizing the solvation environment. Its lipophilicity enables higher adsorption energy, forming a protective interphase. The hydrophobic benzene ring ligands repel H₂O molecules, while the hydrophilic groups attract Zn²⁺ ions, homogenizing their flux. The preferential reduction of Phe before H₂O facilitates the in situ formation of an organic-inorganic hybrid solid electrolyte interphase (SEI), enhancing interfacial stability. This results in improved electrochemical performance, with ZnIIZn cells achieving an extended cycle life of 5250 hours and ZnIILOMO cells retaining 77.3% capacity after 300 cycles, demonstrating significant potential for commercialization.