Integrating Autonomous Vehicles (AVs) with the Internet of Things (IoT) revolutionizes urban transportation in smart cities. This paper investigates how IoT contributes to the networking of AVs and improves transportation efficiency, safety, and sustainability. By utilizing Vehicle-to-everything (V2X) communication, IoT facilitates immediate data sharing among vehicles, infrastructure, and pedestrians, fostering adaptive traffic management and enhanced urban planning. The key elements discussed include sensor integration, data analytics, and communication protocols that power these networks. Case studies from various smart cities showcase effective implementations of IoT-enabled AV networks, emphasizing advantages such as decreased congestion, heightened safety, and reduced emissions. However, despite these advances, issues such as cybersecurity, interoperability, and scalability remain, requiring ongoing research and development. This study highlights the importance of tackling these challenges to fully realize the potential of IoT in the networking of AVs. Ultimately, our findings stress the vital importance of IoT in transforming urban mobility, leading to smarter, more interconnected cities that focus on efficiency and sustainability.