North Tustin is an unincorporated community in Orange County, California. The population was 25,718 at the 2020 census, up from 24,917 in 2010. For statistical purposes, the United States Census Bureau has defined North Tustin as a census-designated place (CDP). It is both the largest CDP and largest unincorporated community in Orange County. The CDP's name was changed from Tustin Foothills in 2005. Located outside the city limits of Tustin, North Tustin has 92705 and 92780 ZIP Codes.