Lyme-Old Lyme High School is a public high school in Old Lyme, Connecticut. It serves grades 9 through 12 and is the only high school operated by Lyme-Old Lyme Schools. The school has a wide range of award-winning groups and athletics programs, including at least 38 clubs. Several clubs including the robotics team and mock trial team compete nationally. In addition, the school ranks number 8 in Connecticut for academics according to U.S. News & World Report, with 67% of student taking one or more APs during their high school career as of 2025.
A successful 2009 referendum cleared the way for a 15,000-square foot expansion of the school that wrapped up in 2013.
LOLHS athletic teams are nicknamed the Wildcats and compete in the Shoreline Conference. The school fields a co-op football team with Valley Regional High School, nicknamed the Warriors.
Lyme-Old Lyme puts on a fall play and spring musical each year.
Lyme-Old Lyme High School's FIRST Robotics Competition Team 236, "The Techno-Ticks", won the Championship Chairman's Award in 2009.