<p>Energy is an essential factor for human survival and development. With the development of new energy sources, the demand for energy storage devices has been increasing. In recent years, supercapacitors have gained more attention in the field of energy storage. Electrodes, as the core components in the energy storage process of supercapacitors, play a crucial role, and the design and preparation of electrode materials are key areas of research. Common electrode materials mainly involve carbon materials, conductive polymers, and transition metal oxides. Among them, cobalt-based nanomaterials are considered a highly promising pseudocapacitive electrode material due to their diverse valence states and excellent electrochemical performance. This article primarily reviews the research status of cobalt-based oxides, cobalt-based sulfides, cobalt-based hydroxides, cobalt-based inorganic salts, and cobalt-based phosphides as electrode materials for supercapacitors from the perspectives of synthesis methods, material morphology, and electrochemical performance. It summarizes the advantages and disadvantages of these materials, modification methods, and discusses the prospects and challenges of cobalt-based compounds and their composite materials in supercapacitor applications. Compared with previous reviews, this work integrates the most recent research findings from 2023 to 2025 and places particular emphasis on morphology control strategies (such as hollow, core–shell, and layered structures), composite design (such as integration with carbon materials or conductive polymers), and the correlation between structural features and electrochemical behavior. The goal is to provide up-to-date theoretical guidance and design strategies for the development of high-performance cobalt-based electrode materials.</p>