Aqueous　zinc　battery　has　low　cost,　environmental　friendliness,　and　safety,　making　it　a　promising　candidate　for　next-generation　battery　systems.　However,　the　Zn　metal　anode　is　impeded　by　a　notorious　dendrite　growth　and　severe　interfacial　side　reactions.　Herein,　a　dendrite-free　deposition　mechanism　based　on　an　interfacial　cyclization　molecular　layer　is　proposed,　which　enables　dendrite-free　Zn　plating　and　lowers　electrolyte　corrosion　by　introducing　trace　methionine　(Met)　into　the　electrolyte.　Different　from　normal　acid-based　additives,　the　Met　can　undergo　cyclization　via　electrostatic　interactions　between　amino　and　carboxyl　groups,　absorbing　on　the　Zn　electrode　surface　and　forming　an　interfacial　molecular　layer,　which　can　not　only　effectively　remove　the　active　H2O　molecules　from　the　electrode　surface　but　can　also　regulate　the　solvated　structure　and　Zn2+-flux　distribution　at　the　interface,　thereby　suppressing　dendritic　Zn　growth　and　side　reactions.　Thus,　the　Zn|Cu　cells　display　a　high　Coulombic　efficiency　of　＞99.4%　over　700　cycles　at　a　current　density　of　1.0　mA　cm-2.　ZnZn　symmetrical　cells　can　also　maintain　a　low　overpotential　over　2600　h　at　a　current　density　of　1　mA　cm-2.　Besides,　the　full　cells　with　V2O5　cathode　exhibit　a　long　cycling　life　and　high　capacity　retention　(＞60.6%　after　1000　cycles　at　0.5　A　g-1).　We　believe　such　an　interfacial　cyclization　mechanism　can　offer　an　avenue　to　design　stable　electrodes/electrolytes　and　may　also　be　expanded　to　other　battery　chemistries.　©　2023　American　Chemical　Society.