The campus opened in 1964 on thirty-three acres of land in West Covina, California, joining two other comprehensive high schools, and eventually one continuation high school to form Covina-Valley Unified School District (C-VUSD). Collectively, the district serves three middle schools, Nine elementary schools, an adult transition program, a trade tech academy, and Children’s Center, which houses three programs: Special Education preschool classes, a General Child Care Program, and County Special Education classes.  The total student population for C-VUSD is approximately 10,000.

The population of South Hills in 1997-98 was approximately 1,500 students. It surged to over 2,000 students in the 2010-2011 school year. However, over the past six years, SHHS has experienced declining enrollment, but has remained steady at approximately 1,650 students, with close to 500 of those students on permits from other districts. The demographics have completely changed since its inception from predominantly Caucasian to Hispanic, with a representational number of students of African-American and Asian Pacific Rim ethnicities. South Hills currently serves a student body with approximately 66% free and reduced lunch.