In this work, novel redox electrolytes based on poly (ethylene oxide) (PEO) were prepared using binary ionic liquid 1‐methyl‐3‐propylimidazolium iodide (MPII) with 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMTFSI) or 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMIMBF4) to reduce the high viscosity of MPII. The addition of low viscosity ionic liquids is to overcome the low mass transportation of redox mediator faced by the single ionic liquid. Therefore, different ratios of ionic liquids were added, and their effect on the electrical properties of the ionic liquid‐based gel polymer electrolytes (GPE) was observed. It was confirmed that all the system dominant by ions rather than electron. The binary ionic liquid system containing 37.5 wt.% of BMIMBF4 showed the highest ionic conductivity of 24.2 mS cm−1. Fourier‐transform infrared and X‐ray diffraction studies confirmed that complexation occurred between all materials. The combination of two alkyl side chain length has enhanced the efficiency of the DSSC with short‐circuit current density (JSC) of 26.81 mA cm−1, open‐circuit voltage (VOC) of 0.67 V, fill factor of 44.5% and photovoltaic conversion efficiency (η) of 7.8%. This work has provided valuable insight for further stability of binary ionic liquid‐based GPE compared to single ionic liquid electrolytes.