Klein Oak High School is a public high school serving students grades 9–12 in unincorporated Harris County, Texas. The school's principal is Thomas Hensley. It was established August 1982.

Klein Oak was the third high school established in Klein Independent School District to serve grades 9 through 12. It is administered by the school district and serves several areas of unincorporated Harris County, including WindRose, Augusta Pines, and Northampton which are zoned to Klein Oak. Since 2004, the school has been home to the only International Baccalaureate Diploma Program in the district.

In 1996, Klein Oak was named a National Blue Ribbon school by the United States Department of Education.