A sustainable dual cross-linked cellulose hydrogel electrolyte was developed for high-performance zinc-metal batteries. This hydrogel, named DCZ-gel, was fabricated using a sequential chemical and physical cross-linking strategy from an aqueous cellulose/alkali hydroxide/urea solution. The hydrogel exhibits excellent mechanical strength (2.08 MPa, 145%) and a porous structure that facilitates ion transport (38.6 mS cm⁻¹). The hydrogel effectively suppresses dendrite growth and side reactions, enabling a stable zinc anode with over 2000 hours of cycling in a Zn|Zn cell. It also supports high-rate and long-term cycling performance in a Zn||polyaniline cell (>2000 cycles at 2000 mA g⁻¹). The hydrogel is easily accessible, biodegradable, and environmentally friendly, making zinc batteries more scalable and sustainable. The hydrogel's unique dual cross-linked structure enhances ion transport and uniformity of the electric field, leading to improved electrochemical performance compared to liquid electrolytes. The DCZ-gel electrolyte demonstrates excellent cycling stability, high ion conductivity, and a high zinc ion transference number, enabling a dendrite-free zinc anode. The hydrogel also suppresses side reactions such as zinc corrosion and hydrogen evolution. The DCZ-gel electrolyte outperforms other electrolytes in terms of cycling life, rate capability, and Coulombic efficiency. The Zn||PANI cell using the DCZ-gel electrolyte achieves a high reversible specific capacity of 160 mAh g⁻¹ at 500 mA g⁻¹ and a high-capacity retention of 85% after 2000 cycles at 2000 mA g⁻¹. This work presents a promising approach for developing sustainable and high-performance cellulosic electrolytes for green energy storage and conversion.A sustainable dual cross-linked cellulose hydrogel electrolyte was developed for high-performance zinc-metal batteries. This hydrogel, named DCZ-gel, was fabricated using a sequential chemical and physical cross-linking strategy from an aqueous cellulose/alkali hydroxide/urea solution. The hydrogel exhibits excellent mechanical strength (2.08 MPa, 145%) and a porous structure that facilitates ion transport (38.6 mS cm⁻¹). The hydrogel effectively suppresses dendrite growth and side reactions, enabling a stable zinc anode with over 2000 hours of cycling in a Zn|Zn cell. It also supports high-rate and long-term cycling performance in a Zn||polyaniline cell (>2000 cycles at 2000 mA g⁻¹). The hydrogel is easily accessible, biodegradable, and environmentally friendly, making zinc batteries more scalable and sustainable. The hydrogel's unique dual cross-linked structure enhances ion transport and uniformity of the electric field, leading to improved electrochemical performance compared to liquid electrolytes. The DCZ-gel electrolyte demonstrates excellent cycling stability, high ion conductivity, and a high zinc ion transference number, enabling a dendrite-free zinc anode. The hydrogel also suppresses side reactions such as zinc corrosion and hydrogen evolution. The DCZ-gel electrolyte outperforms other electrolytes in terms of cycling life, rate capability, and Coulombic efficiency. The Zn||PANI cell using the DCZ-gel electrolyte achieves a high reversible specific capacity of 160 mAh g⁻¹ at 500 mA g⁻¹ and a high-capacity retention of 85% after 2000 cycles at 2000 mA g⁻¹. This work presents a promising approach for developing sustainable and high-performance cellulosic electrolytes for green energy storage and conversion.