Green roofs with urban farming can make buildings in cities more sustainable by helping the environment, communities, and food systems. Research on rooftop farming in urban cities like Hong Kong shows that it can reduce environmental problems, improve community functions, and support urban food systems. Examples from around the world demonstrate the benefits and potential of rooftop urban farming. The study also looks at the challenges and opportunities for urban farming in cities like Hong Kong. This information can help make buildings and environments in urban cities more sustainable.