In this study, we fabricate a simple, low-cost, high-efficiency, and easy-to-design electrochromic device. Multilayer graphene (MLG) samples were obtained by chemical vapor deposition method (CVD) at four different growth temperatures of 900 , 950 , 1000 , and 1050 ∘ C . Electrical and optical characterizations of MLG samples were carried out by transferring them to the polyvinyl chloride (PVC) surface by thermal lamination method. After the characterization of the samples the so called coplanar surface is produced in order to obtain an efficient electrochromic device consisting of a flexible graphene surface without an extra electrode Optical measurements show that threshold voltage for the change in the optical modulation is 2.5 V in the near-infrared region and that there exists an increase of 60 % just over 3 V value. Also, in the electrical characterization studies, a decrease of up to approximately 50 % of the layer resistance was seen. • Multilayer graphene thin films were obtained by CVD method. • The device structure consisting of the graphene surface, which we call the coplanar structure, was developed. • A low-cost, easy-to-build, high-efficiency, flexible electrochromic device has been designed”. • Experimental results show that there was an increase of 60% in optical modulation value after the 3 V value and a decrease of up to approximately 50% of the layer resistance.