Recently, in response to the challenges related to energy development and environmental issues, extensive efforts are being made towards the development of supercapacitors based on green and sustainable resources. Aerogel electrodes offer high energy/power autonomy, fast charge-discharge rates, and long charge/discharge cycles over composite film electrodes due to their unique structure, ultra-lightness, high porosity, and large specific surface area. Nanocellulose (NC), a sustainable nanomaterial, has gained popularity as a supercapacitor electrode material owing to its remarkable properties such as biodegradability, tunable surface chemistry, ability to develop 3D aerogel structures, etc. This comprehensive review summarizes the research progress on developing NC-based aerogels for supercapacitor applications. First, the fundamentals of NC extraction from cellulose sources and aerogel processing routes are discussed. An attempt is made to correlate the electrochemical performance of NC-based electrodes with their aerogel structures. Finally, challenges and future prospects for the advancement of NC-based aerogels are addressed.