Rowland Heights is an unincorporated area in and below the Puente Hills in the San Gabriel Valley, in Los Angeles County, California, United States. The population was 48,231 at the 2020 census. Rowland Heights is in the Los Angeles metropolitan area and represented by the County of Los Angeles and is the second largest census designated place in Los Angeles County by area, behind Topanga, and the county's fifth largest CDP by population.