Diamond Bar High School (DBHS) is a public high school located in Diamond Bar, California, as part of the Walnut Valley Unified School District.

Diamond Bar High School's mascot is the Brahma, and the school colors are purple and gold. Diamond Bar High School students participate in programs such as Advanced Placement (AP) and International Baccalaureate (IB). During the school year, DBHS received an Academic Performance Index of 870, and 97% of students passed the California High School Exit Exam in 2008-2009. Most of Diamond Bar High School's students come from Chaparral Middle School and South Pointe Middle School, both located in Diamond Bar.