In this chapter, it is focused to highlight the importance of fabricating nanocomposites as active materials for supercapacitor applications. This chapter begins with a general introduction about the necessity of energy storage, and it presents the types of electrical energy storage devices. Supercapacitor is reckoned to be the best storage device when compared with other storage devices (electrostatic capacitor, battery, fuel cell) due to the following features such as high power density, higher cycle life, high rate capability, and less maintenance. Various electrode materials used in supercapacitors, such as carbon-based materials, metal oxides, and conducting polymers, are discussed. Besides, it emphasizes the use of nanocomposite toward the enhancement of the electrochemical performance of the supercapacitors. Next, various synthesis techniques for preparing nanocomposites are reported, and the chapter ends with applications of the supercapacitor.