Rechargeable aqueous zinc-ion batteries (AZIBs) are considered the most promising electrochemical energy storage technologies due to their high safety and low cost. However, their practical application is hindered by persistent challenges at the Zn anode, including thermodynamic corrosion, hydrogen evolution, and dendrite growth in aqueous electrolytes. In this work, a nonionic molecule, n-octyl β-D-glucoside (8TG), is investigated as an additive for ZnSO₄ (ZS) electrolyte system. Experimental and theoretical calculations confirm that 8TG molecules tend to adsorb on the (001) plane of zinc hydroxide sulfate (ZHS), lowering its interfacial energy and thereby inducing lateral growth to form a dense protective layer. This layer exhibits an interlayer spacing of > 8 Å and is rich in anions, which can lower the energy barrier for ion transport through an electrostatic repulsion–attraction effect. Furthermore, 8TG preferentially adsorb on the Zn₍₀₀₂₎ and Zn₍₁₀₀₎ facets during zinc electrodeposition. Through a spatial confinement effect, it guides the preferential deposition of Zn²⁺ along the Zn₍₁₀₁₎ plane, effectively suppressing dendrite growth. Benefiting from these multifunctional effects of 8TG, Zn||Zn symmetric cells achieve a lifespan exceeding 2500 h at 2 mA·cm⁻² and 1 mAh·cm⁻², and maintain stable operation over 400 h even under 10 mA·cm⁻² and 5 mAh·cm⁻². Moreover, Zn||I₂/MnO₂@activated carbon (AC) full cells assembled with 8TG additive exhibit nearly 100% capacity retention after 500 cycles. This work systematically elucidates the influence of 8TG additive on the growth orientation of ZHS and Zn dendrites, providing new insights into exploring electrolyte additives for high-performance AZIBs.