WhiteOS is an AI-powered Urban Intelligence Operating System that integrates real-time public and private urban data in a digital twin to support monitoring, forecasting, simulation, and operational decision-making. The platform combines population, mobility, public transit, traffic, CCTV, weather and event data in a unified spatial view. GeoAI and spatio-temporal AI analyze urban conditions and forecast population changes across the next 12 hours. A spatial ontology, GeoRAG, and an LLM-based agentic AI interface help operators interpret local conditions and compare response scenarios before taking action. Designed for national and municipal safety agencies, city administrators, and field teams, WhiteOS supports operations and event safety management, turning fragmented data into coordinated action while keeping final authority with operators.