This research explores the potential of the Internet of Things (IoT) to enhance security and sustainability in smart cities. It addresses the limitations of current smart city solutions, such as inadequate monitoring, security vulnerabilities, and lack of sustainability. The study aims to identify advanced approaches to improve environmental monitoring, enhance security through effective detection and access control, and promote sustainability by optimizing resource utilization. By leveraging IoT technologies, this research seeks to create a safer, more sustainable, and citizen-centric smart city environment.