Developing a gel polymer electrolyte (GPE) combining with superior mechanical strength and lithium-ion transportation properties is still a challenge. Herein, a new GPE based on polyethylene glycol (PEG) entrapped in cross-linked cellulose structure is prepared via one-step crosslinking method. The results showed that the composite gel membrane owned superior tensile strength from 33.92 MPa to 211.06 MPa and bending resistance when the content of PEG was changed from 2.5% to 20%. It exhibited considerable ionic conductivity of 3.31 × 10−3 S cm−1, together with an outstanding lithium-ion transfer number of 0.63 when the content of PEG was at 5%. The assembled Li/GPE/NCM523 batteries by this gel polymer electrolyte demonstrated initial discharge capacity of 159.3 mAh g−1 as well as the coulomb efficiency of 85.52% at 0.2C. Moreover, the as-prepared GPEs possessed good affinity with electrodes. Combing the high performance and optimized mechanical strength, we anticipate the possibility of this cost-effective and biodegradable GPE membranes applied in LIBs can be achieved. Display omitted •A sustainable cellulose/PEG composite gel membrane was successfully prepared via one-step crosslinking method.•The GPE based on this composite membrane possessed excellent tensile strength and bending resistance.•The high electrolyte uptake, ionic conductivity and transport number were obtained.•The assembled cells showed good electrochemical performance.