Ultracapacitors, as state-of-the-art energy storage solutions, have garnered immense interest owing to their outstanding power density, swift charge–discharge capabilities, and extended cycling stability. Metal oxides have emerged as potential options among the numerous materials investigated for supercapacitor electrodes due to their distinct electrochemical characteristics and abundance. The goal of this study is to provide a thorough examination of the most recent, cutting-edge studies on metal oxides for supercapacitor applications. The review provides a concise summary of the fundamental ideas behind the operation of supercapacitors, placing special emphasis on the part played by metal oxides in the electrochemical double-layer capacitance and pseudo-capacitance mechanisms. It provides an in-depth examination of various metal oxides utilized as supercapacitor electrodes, including transition metal oxides (e.g., \({\text{RuO}}_{2}\) , \({\text{MnO}}_{2}\) , and \({\text{Co}}_{3}{\text{O}}_{4}\) ) and mixed-metal oxides, highlighting their distinctive advantages and limitations. In addition to the material aspects, the review also covers recent breakthroughs in electrolyte optimization and device architecture design, which play a vital role in achieving higher energy densities and extended cycle life. Strategies to address the challenges of metal oxide-based supercapacitors, including capacity fading and rate capability, are presented along with potential solutions proposed in the literature. This paper also explores current developments in the design and production of nanomaterials, which have made it possible to precisely regulate the morphology and structure of metal oxide electrodes, leading to improved electrochemical performance. The crucial elements influencing the performance of supercapacitors/ultracapacitors, such as electrical conductivity, specific surface area, and pore size distribution, are covered in detail. In conclusion, metal oxides have proven to be quite useful as supercapacitor electrode materials. This review serves as an invaluable resource for researchers, engineers, and stakeholders looking to comprehend and explore the enormous potential of metal oxides in advancing supercapacitor technology towards workable energy storage solutions by providing a critical and thorough analysis of the current research landscape.