Redondo Union High School (RUHS) is a public high school in Redondo Beach, California.
Redondo Union High School is a part of the Redondo Beach Unified School District. All residents of Redondo Beach are zoned to Redondo Union. In addition, residents of Hermosa Beach may choose to attend Redondo Union or Mira Costa High School of the Manhattan Beach Unified School District.
Since opening in 1905, Redondo Union High School has developed into the second largest high school campus in the State of California, with an overall area of .
Redondo Union High School was organized in the summer of 1905. The first classes were held in two upstairs rooms of the Masonic Building in Redondo Beach. In December of that same year, a site known as Old Chautauqua Place was selected as the location for the school.
In 1939, the Science Building was dedicated. Residents of Manhattan Beach attended Redondo Union until 1950, when Mira Costa High School opened.
Redondo Union High School was a part of the South Bay Union High School District until 1993, when it dissolved.
In 2013, RUHS Boys' Basketball won the Division II CIF State Championship.
In 2014 and 2015, the Girls' Volleyball team won the CIF State Championship.
In 2024, the RUHS Boys' Volleyball team won their first CIF Division II State Championship.
In 2025, the Redondo Union High School Chinese Program received the National Outstanding K-16 Chinese Program Award by the Chinese Language Association of Secondary-Elementary Schools (CLASS). This national honor recognizes programs that demonstrate excellence in curriculum innovation, student achievement, community engagement, and the sustainable development in Chinese education.