The school opened on September 7, 1923. In July 1924, Fr. Charles Conley was appointed pastor of St. Mary’s parish and was named superintendent of the school. Enrollment increased during that year and 6 acres of property adjacent to St. Vincent's orphanage was acquired to build an independent high school. On September 6, 2007, Thomas G. Doran, the Bishop of Rockford, renamed the three Catholic schools in Freeport to Aquin Catholic Schools, and their campuses are now referred to as the Junior-Senior High Campus, the Elementary Campus, and the PreSchool Campus. The name was changed to Aquin High School at the start of the 1924 school year.
Traditions
The school's prom is open to 11th and 12th grade students. Since 1926, the high school has a special prom assignment system used so each student has a date during prom and so cohesion increases among the students. The nuns operating the school first created the tradition, in part to provide inclusion for the students who attended Aquin from St. Vincent's Orphanage, and as years passed other elements became a part of the annual event. On the day prom dates are assigned, the school places female students in the gymnasium and the male students in the library. The female students wear paper bags so the male students, when they see them, will not know who is who. Each male student, dressed in a formal outfit or a special costume, draws the name of a female student randomly from a hat. The male students later perform skits about their prom dates. After the skits are over the male students ask the females to be their prom dates. The female students give gift bags to the males, and some males also have gift bags for the females. In 2017 Michelle Gallagher, who served as the junior class adviser, stated "It's less of a date and more like something fun to do with your classmates."
Athletics
The Bulldogs compete in the Northwest Upstate Illini Conference. They participate in several IHSA sponsored athletics and activities, including; football, girls cross country, girls volleyball, boys & girls basketball, boys & girls golf, boys baseball, girls softball, and girls swimming and diving.
Teams
The following teams finished in the top four of their respective IHSA sponsored state championship tournaments:
Football:
1A State Champions 1A State Champions 1A State Champions
