Millbrae is a city in northern San Mateo County, California, United States. To the northeast is San Francisco International Airport; San Bruno is to the northwest, and Burlingame is to the southeast. It is bordered by San Andreas Lake to the southwest. The population was 23,216 at the 2020 census. Millbrae has Sister City relationships with La Serena, Chile and Mosta, Malta, as well as a friendship city agreement with Hanyu, Japan, Taishan, China, Ramallah, Palestine, and Dongguan, China.