It opened in 1888 as the sole high school serving what was then the independent city of Allegheny.

An annex was added in 1904 and the original 1888 building was replaced by a new Art-Deco-style structure in 1936.

The surviving 1904 and 1936 buildings, which were designed by Frederick J. Osterling and Marion M. Steen respectively, were listed on the National Register of Historic Places in 1986.

Notable Allegheny High graduates include William N. Robson, award-winning writer, director, and producer from the old-time radio era[5] and Dorothy Mae Richardson, an African American community activist whose work was essential to the founding of the Neighborhood Reinvestment Corporation.

American novelist Willa Cather taught English and Latin at Allegheny High School, where she came to head the English department.