"Largest Cities of the World - by population". worldatlas.com. Retrieved 2008-10-22. Including population within the recognized metro area of the city and also people living in the immediate surrounding area outside of the established border of the city the most populated cities in the world are: 1. Tokyo, Japan - 28,025,000, 2. Mexico City - 18,131,000, 3. Mumbai, India - 18,042,000, 4. São Paulo, Brazil - 17, 711,000, 5. New York City, USA - 16,626,000.