Archbishop Riordan High School is a diocesan, co-ed Catholic high school established by the Society of Mary in San Francisco, California. It is part of the Archdiocese of San Francisco. It opened in fall 1949 as Riordan High School, named after Archbishop Patrick William Riordan, the second Archbishop of San Francisco; "Archbishop" was officially added to its name in 1990.

Riordan was the oldest exclusively male high school in San Francisco until it became coeducational in 2020.