<p>Two-dimensional (2D) inorganic materials have emerged as transformative platforms for sensor and energy technologies, owing to their atomic-scale thickness, high surface area, and the apparent sensitivity of their electronic structure to external stimuli. This review provides a comprehensive evaluation of the featured 2D materials—graphene, silicene, and borophene and highlights their role in gas, moisture, and electrochemical sensing, as well as their role in energy storage and interfacial energy applications. Production strategies, surface chemistries, and stabilization approaches were systematically compared. Then, detection mechanisms, device architectures and performance criteria are discussed in depth. The potential of these materials in supercapacitors, battery electrodes, and electrochemical interfaces, is critically evaluated with special emphasis on advantages, limitations, and scalability. Key application challenges such as environmental stability, material aging, and integration into practical systems are examined. While the analysis highlights graphene as the most mature and widely adopted 2D material, it highlights that silicene and borophene, despite their high theoretical performance, remain limited by stability and synthesis barriers. Overall, this review provides a holistic view of the status and future directions of graphene, silicene, and borophene-based sensor and energy systems. It aims to guide both fundamental research and technological development.</p>