Abstract The integration of several sources, microgrids, distributed generation, and various load types are supported owing to efficient control and management capabilities of smart grid. On the other hand, Internet of Things (IoT) is experiencing marvelous advances in terms of architecture, network types, and device compliance in a wide variety. The software related improvements of IoT are also extremely remarkable since many novel protocols, standards, connectivity methods, and security precautions are implemented. In this chapter, a comprehensive introduction on IoT-based smart grid infrastructures is presented. The technological developments are achieved in communication and security issues that enable the integration of smart grid and IoT systems. The smart grid applications and driving factors of IoT for smart grid systems are examined in depth that all stages of the smart grid system starting from generation to consumption levels are systematically analyzed. The IoT applications enabled in smart grid system in terms of application areas such as smart cities, smart home applications, home energy management systems, energy harvesting issues, smart sensor networks, distributed generation, and microgrid have been discussed. Finally, the open issues, future research directions, and report several important research areas are presented.