Hacienda Heights is an unincorporated community in the San Gabriel Valley of Los Angeles County, California, United States. As of the 2020 census, the community had a total population of 54,191, up from 54,038 at the 2010 census. For statistical purposes, the Census Bureau has defined Hacienda Heights as a census designated place (CDP). It is the third largest CDP in Los Angeles County by area, behind Topanga and Rowland Heights, and the county's fourth largest CDP by population.