The persistent requisite for clean and ecological energy alternatives has been highlighted by the diminution of relic energy resources and the escalating issues related to environment conservation. Batteries and supercapacitors are the most prominent candidates considered to fulfill today’s need for clean and renewable energy. The way of energy storage in both of these devices is commonly referred to as electrochemical energy storage. However, the decisive augmentation of electrochemical activity in these types of energy storage devices depends on several factors. This includes a large specific surface area, a regimented-organized configuration, effective functionalization, and substantial porosity of that material. These attributes have proven essential in enhancing electrochemical energy storage performance. Two-dimensional materials are specifically enriched with these features. Among 2D materials, nanostructured MXenes have gained recognition as promising candidates for energy storage applications. This is due to their distinctive properties, including high electrical conductivity, unique structure, abundant active sites, hydrophilicity, large surface area, and exceptional mechanical strength. Through this chapter, we aimed to discuss the mechanistic approaches employed in the design, synthesis, and utilization of nanostructured MXenes for energy storage, particularly in batteries and supercapacitors. The discussion encompasses the fundamental understanding of the fundamental features of MXene beneficial for energy-related applications and surface electrochemistry. Furthermore, various synthesis methods, including exfoliation, intercalation, and chemical functionalization, are elucidated to tailor the morphology and properties of MXenes for enhanced energy storage performance. Furthermore, insights into the electrochemical mechanisms governing charge storage, ion diffusion, and stability in MXene-based electrodes are provided. A widespread gestalt of the mechanistic understanding and encroachments in utilizing nanostructured MXenes for efficient energy storage systems was provided, and related challenges with prospects were discussed finally.