Allen High School is a public, co-educational secondary school in Allen, Texas (United States). It is the only high school in the Allen Independent School District.

Allen High School serves most of the city of Allen. Until fall 2006, when Lovejoy High School opened, Allen High School served high school students in the Lovejoy Independent School District, which includes the city of Lucas, most of Fairview, a portion of Parker and a small portion of Plano.