The rapid advancement of modern technologies, including mobile electronics and electric vehicles, drives the growing demand for energy storage devices. Due to their complementary performance characteristics, supercapacitors (SCs) and batteries have become increasingly vital among various storage systems. As a result, there is significant interest in developing new, cost-effective, environmentally friendly, high-performance materials to enhance the capabilities of current SC technologies. Nanostructured metal oxides (NMOs) have emerged as auspicious electrode materials for SCs, owing to their abundant redox activity, tunable morphologies, and high theoretical capacitance. This work presents a comprehensive overview of SC fundamentals, including device design, fabrication processes, and the synthesis and integration of NMOs for improved energy storage performance. Special attention is given to various synthesis strategies that enable precise control over key material characteristics, including particle size, crystallinity, porosity, and surface area. This chapter also introduces the critical factors that influence electrochemical performance, including material crystallinity, electrical conductivity, interfacial properties, and overall composite architecture, offering insights for the rational design of next-generation SC electrodes.