Union High School may refer to:

United States

• Natchez Union High School, Natchez, Mississippi
• Redondo Union High School, Los Angeles, California
• Union High School (Modoc), Modoc, Indiana
• Union High School (Dugger), Dugger, Indiana
• Union High School (Iowa), La Porte City, Iowa
• Union High School (Grand Rapids, Michigan)
• Union High School (Missouri), Union, Missouri
• Union High School (New Jersey), Union Township, Union County, New Jersey
• Union High School (North Carolina), Delway, North Carolina
• Union High School (Oklahoma), Tulsa, Oklahoma
• Union High School (Oregon), Union, Oregon
• Union High School-Main Street Grammar School, Union, South Carolina
• Union High School (Utah), Roosevelt, Utah
• Union High School (Big Stone Gap, Virginia)
• Union High School (Camas, Washington)
• Union High School (Black River Falls, Wisconsin)

South Africa

• Union High School (Graaff-Reinet), Eastern Cape, South Africa