St. John's High School is a Roman Catholic private high school located in Delphos, Ohio, United States. It is located in Allen County, and is part of the Roman Catholic Diocese of Toledo. The school's mascot is the Blue Jay. The school is associated with the Midwest Athletic Conference for sports.

Ohio High School Athletic Association State Championships

• Football - 1997, 1998, 1999, 2005, 2008, 2010
• Boys Basketball – 1949, 1983, 2002
• Girls Basketball – 1977, 1979, 1980, 1987, 2002
• Boys Golf - Andy Miller 1998

Notable alumni

• Tom Nomina, former defensive tackle for the Denver Broncos and the Miami Dolphins