Benet Academy ( BEN-et) is a private, highly competitive, co-educational, college-preparatory, Benedictine high school in Lisle, Illinois, United States, overseen by the Diocese of Joliet. Founded in 1886, the school was initially established in Chicago as the all-boys St. Procopius College and Academy by Benedictine monks, who also operated the St. Joseph Bohemian Orphanage. In 1898, the orphanage moved to Lisle, about 25 miles (40 km) west of Chicago, to be joined by St. Procopius three years later. In 1926, Benedictine nuns constructed the all-girls Sacred Heart Academy near the orphanage and school in Lisle. The orphanage closed in 1956 to make room for St. Procopius Academy, which separated from the college in 1969. Due to rising costs and waning enrollment, Sacred Heart merged with St. Procopius Academy in 1967 to form Benet Academy on the St. Procopius campus. Since then, numerous building projects have been undertaken to expand Benet's athletics, music, and science programs.

Admission is competitive and relies on entrance exam scores, transcripts, and performance on standardized tests. All students complete a college-preparatory curriculum and may earn college credit through programs including Advanced Placement. As of 2023, Benet's average ACT test score regularly exceeds state and national averages, and more than 99 percent of students go on to college after graduation. The school's academic program has been featured in reports by the Chicago Sun-Times and U.S. News & World Report.

Notable alumni of the school include Bishop Robert Barron, NBA player Frank Kaminsky, Jim Ryan, and Grammy-winning singer Dave Bickler.