AI presents transformative opportunities for urban science and management, leveraging massive multimodal datasets to optimize infrastructure, predict trends, and enhance resilience. Conversely, urban science fosters AI development by embedding context-awareness and human-centered insights, thereby equipping algorithms to address complex spatial dynamics. Illustratively, digital twins enable real-time urban analytics, while generative AI facilitates inclusive urban modeling. Ultimately, the synergy between CityAI and urban science paves the way toward smarter, fairer, and more sustainable cities.