Aliso Viejo is a city located in the San Joaquin Hills of southern Orange County, California, in the United States. It was officially incorporated as the 34th city in Orange County on July 1, 2001, making it the only city in the county to be incorporated since the year 2000.
The city is bordered by Laguna Beach to the west and southwest, Laguna Hills to the east, Laguna Niguel to the southeast, and Laguna Woods to the north. According to the 2020 census, Aliso Viejo had a population of 52,176, an increase from the 47,823 residents recorded in 2010.