Which city-state has the largest population?

The city-state with the largest population is Singapore. It has roughly six million residents, making it vastly more populous than the sovereign city-states of Monaco and Vatican City.

Singapore occupies the southern tip of the Malay Peninsula and includes a heavily urbanized main island plus smaller offshore islands. Its modern population grew rapidly after the port was founded as a British trading settlement in 1819. Singapore became self-governing in 1959, joined Malaysia in 1963, and became an independent republic in 1965.

Hong Kong is the common mix-up. It has a population larger than Singapore’s, but it is not an independent city-state: it is a special administrative region of China. Singapore, by contrast, is both a city and a sovereign country. Monaco is another genuine city-state, but it has only tens of thousands of residents, while Vatican City has fewer than 1,000.