The rapid advancement of digital technologies has significantly transformed modern infrastructure systems, leading to the emergence of Internet of Things (IoT)-based smart infrastructure. IoT enables the integration of physical devices, sensors, communication networks, and data analytics to enhance the efficiency, reliability, and sustainability of infrastructure systems. Smart infrastructure systems are increasingly being adopted in areas such as transportation, energy management, urban planning, water systems, and industrial automation. These systems facilitate real-time monitoring, predictive maintenance, and intelligent decision-making, thereby improving operational performance and reducing costs. This study explores the innovations and engineering applications of IoT-based smart infrastructure systems. It examines the role of IoT technologies in enhancing infrastructure efficiency, sustainability, and user experience. The research adopts a descriptive methodology supported by primary survey data and secondary literature to analyze the effectiveness and adoption of IoT-based solutions. The findings indicate that smart transportation systems, smart grids, and intelligent building management systems are among the most impactful applications of IoT in infrastructure development. The study also highlights challenges such as data security concerns, high implementation costs, lack of standardization, and technical complexity. Despite these challenges, increasing technological advancements, government initiatives, and urbanization trends are expected to drive the growth of IoT-based smart infrastructure systems. This research provides valuable insights for engineers, policymakers, and researchers seeking to develop innovative and sustainable infrastructure solutions for future development.