A graphene electrode with a novel in-plane structure is proposed and successfully adopted for use in supercapacitor applications. The in-plane structure allows the electrolyte ions to interact with all of the graphene layers in the electrode, thereby maximizing the utilization of the electrochemical surface area. This novel structure contrasts with the conventional out-of-plane stacked structure for such supercapacitors. We herein compare the volumetric capacitances of in-plane and out-of-plane structured devices with reduced multi-layer graphene oxide films as electrodes. The in-plane structured device exhibits a 2.5-times higher capacitance than the out-of-plane structured devices. Therefore, this study demonstrates the potential of in-plane structured supercapacitors with high volumetric performances as ultra-small energy storage devices.