The Internet of Things (IoT) has become a cornerstone for enabling smart cities, an innovative futuristic approach to urban management that respects enhanced services and improved quality of life in this new era as societies continue their rapid movement towards becoming predominantly urban. However, the massive increase in number of IoT devices also brings major cybersecurity concerns that can compromise these infrastructures security and functionality. Smart cities and the importance of Zero-Trust security involves analyzing how Artificial intelligence (AI) plays an important in securing smart cities. We define smart cities and their basic items which include among others, the transportation system, energy saving or even security systems while also showing applications of IoT devices related to urban area benefits. It then evolves into talking about the common cybersecurity threats these infrastructures face, through use cases like 2016 Dyn attack which further highlight how insecure IoT systems are. To overcome these risks, we review a set of AI solutions for stronger cybersecurity, such as machine learning algorithms to identify impending threats or malicious activity; anomaly detection systems that track activities at scale impossible through manual logging efforts; and predictive analytics on storage patterns (including proven usage insights) to implement security measures ahead of time. It also outlines how AI is integrated into automated incident monitoring and advanced user authentication, providing an interesting model for improving IoT security in practice. We use case studies from cities such as Barcelona that show how those benefits can be made tangible when AI is integrated into urban security strategies. Finally, we discuss ethical issues including data privacy from the perspective of a smart city and summarize regulatory frameworks that need to be established ensure citizens rights protection in smart cities. Accordingly, this article concludes with the assertion that utilising AI in cybersecurity strategies for smart cities is necessary to protect urban spaces from ever evolving cyber threats.