Homes in the
Lemont HS district.

Lemont High School traces its roots to the turn of the century. An old surviving document shows graduates as early as 1891, though the school was not officially formed until 1906, when five students began meeting in a leased building on McCarthy Road. By 1925, after several failed attempts, a building was completed at 800 Porter Street, where the school still stands today. Enrollment nearly doubled in the 1950s, driving a series of expansions that grew the campus to roughly 30 acres by the late 1960s. A major 2006 construction project added classrooms, a turf football stadium, and a Performing Arts Center, and in 2017 Lemont High School was named a National Blue Ribbon School as an Exemplary High Performing School.

Lemont High School offers approximately 200 course offerings across nine academic departments, with Honors and Advanced Placement courses available in most curricular areas. Students can also access vocational programs through the Wilco Area Career Center in Romeoville, of which Lemont is a member, and the school runs a Block 8 schedule with eight courses meeting every other day. The class of 2016 earned an average composite ACT score of 23.3, and nearly 94 percent of that graduating class enrolled in post high school continuing education. In 2017 the school earned National Blue Ribbon status, placing among the top performers on Illinois state assessments.

Lemont competes in the South Suburban Conference and is a member of the Illinois High School Association. The school has built a strong athletic tradition, especially in baseball, softball, wrestling, and cheerleading. The baseball team won IHSA state championships in 2014 and 2016, and the softball team captured back-to-back Class 3A state titles in 2022 and 2023. The wrestling program won a team state championship in 2020, while the competitive cheerleading squad has claimed multiple state titles. The football team reached the state final three times in the late 2000s and mid-2010s.