Grafton High School is a secondary school in Grafton, Wisconsin. It is part of the Grafton School District. The only public high school in Grafton, it has a student enrollment of around 700.

Grafton High School provides students with educational opportunities such as core subjects, technology education, physical education, and the fine arts. In Jay Mathews' 2005 Challenge Index, GHS ranked 461st out of 1062 in the country. This was third in the state and first in the conference. In 2006, GHS was ranked 559th in the country and fifth in the state.

In 2009, industrial technology teacher, Carl Hader, was named Wisconsin High School Teacher of the year. As automotive instructor, he has guided GHS students to first-place finishes in several state and national auto repair competitions.

In 2010, Biology, Earth Science, and Anatomy teacher, Fran Grant, was named the state of Wisconsin Biology Teacher of the year.

Grafton High School participates in the North Shore Conference.

• The football team won state championships in 1981 and 1982. They were state runner-up in 2023.
• The girls' basketball team made appearances at the state tournament in 1991 and 1993. In 2007, it won its first state championship, beating New London in overtime. The team also went to state in 2008, but lost in the semi-final round in overtime. In 2009 the Grafton girls won the state championship for the second time.
• The boys' soccer team made state appearances in 1993, 1998, 1999, 2000, 2006 and 2015 finishing second three times. In 2006, it was runner-up in the state soccer tournament, losing to Xavier High School.
• The girls' soccer team won a state championship in 1997 and made state appearances in 2003, 2004, 2008, 2009, 2010, 2011 and 2012.
• The Grafton boys track team won the state Division 2 title in 2000 and took second in 1999 and 2004. They participated in the Penn Relays on the University of Pennsylvania track in 2005, finishing first in their heat in the 4x800 and taking 13th overall. They left the relays ranked in the top 25 nationally.
• The girls' swimming team was state runner-up in 2003 and 2008 and state champion in 2004 and 2005, while taking third in 2006. The girls' swimming team was also WIAA Division 2 state champions in 2013 and 2014.
• The Grafton Competition Cheerleading team won the state competition 6 years in a row from 2005 to 2010
• The boys’ golf team was state runner-up in 1999 in Division 2 falling to New Richmond.
• The boys rugby club won the 2017 Division 2 State Championship.

• Beau Benzschawel, American football player
• Dave Levenick, American football player
• Rich Strenger, American football player

In May 2019, Grafton High School was scheduled to host a talent show. Unfortunately, due to low interest and support, the event was ultimately canceled. Despite efforts to promote the talent show and encourage participation, organizers were unable to generate enough enthusiasm from the student body and community to make the event viable. However, Grafton High School remains committed to providing engaging extracurricular opportunities for its students and looks forward to exploring new ways to showcase their talents in the future.

• Grafton High School website