The boundary change is being phased in gradually and will not take full effect until the 2025–26 school year, when all students from the reassigned neighborhoods will be attending Langley.

The average SAT score for McLean's Class of 2024 was 1308 (including both Critical Reading and Writing and Math), the second-highest among Fairfax County's 25 high and secondary schools.

[23] In 2017, The Highlander was one of 49 high school publications nationwide to be named a finalist for the National Scholastic Press Association's Pacemaker Award.

[27] Individual articles that have received recognition have addressed topics such as refugees in Northern Virginia, gender identity, and student-athletes with concussions.

In 2004, The Clan was inducted into the National Scholastic Press Association Hall of Fame after ten years of consecutively being "All American".

In 2024, McLean High School received the Virginia Music Educators Association (VMEA) Blue Ribbon Award, which "recognizes achieved excellence in Band, Orchestra, and Choral Performance.

"[29] McLean High School also regularly sends students to All-Virginia band, orchestra, and choir ensembles.

From 2006 to 2012, they were coached by John Thomas (MHS '96, Virginia '00) and compiled a 60–31 record and district and regional playoff berths yearly.

The Highlanders failed to win the District, falling to James Madison High School in the title game.

In 2019, Dowling's baseball team won the Liberty District championship by defeating Yorktown High School.

[42] In 2024, the McLean baseball team, still under Dowling, won the VHSL Class 6 state title, defeating South Lakes High School 15-5 in the championship game.

[44] In the 2011–12 season, under Roller, the Highlander boys won the Liberty District in a double-overtime victory over Fairfax High School.

[46] The team had another winning season under Roller in 2012–13, finishing the year as the district runner-up and again making it to the regional playoffs.

The girls' team defeated South Lakes High School to win the Liberty District championship in 2018–19, compiling an 18–7 record.

[54] In Deegan's first year as coach, the McLean girls again won the 2023-24 Liberty District title, once more defeating rival Langley in the championship game.

In 2022, the boys' crew team's first varsity eight finished second to Wakefield High but again won the overall points trophy at the VSRA championships.

In 2023, the boys' crew team returned to form, and won the first, second, third, and fourth varsity races at the VASRA championships.

McLean's football team finished the 1980 season 10–1, led by future Notre Dame and New York Giants player Eric Dorsey.

After an 0–10 campaign in 2008, the 2009 team rebounded to 6–5 and made the Northern Region playoffs, losing in the first round to Robert E. Lee High School.

The Highlanders then went over to Arlington the following week for the playoffs and fell to the eventual Division 5 runner-up Yorktown High School 20–6.

[65] The Highlanders are a founding member of the Northern Virginia Scholastic Hockey League and have made the playoffs at least nine times.

Under the guidance of head coach John Sherlock, the Highlanders advanced to the 2010–2011 NVSHL championship game before falling 7–2 to the Stone Bridge Bulldogs.

[67] The boys' team, currently coached by Leland Jameson, has been one of the stronger programs in the Northern Region in recent years.

[71] In the spring of 2023, McLean's girls' softball team was the Liberty District champion,[72] and went on to win the VHSL Class 6 State championship.

[73] The Highlander swim team has enjoyed success in the past several years, winning the Liberty District Championships in 2021 and 2024.

[77][78] The Highlanders girls' volleyball team, coached by Samantha Stewart, won the Liberty District title in 2021 and advanced to the Northern Region final.

[80] The Highlanders boys' volleyball team was created in 2024,[81] and won the Liberty District and Northern Region titles in their inaugural year.

It is more likely that the name was inspired by the Union forces of the 79th New York "Highlanders", formed largely by Scottish immigrants and known for their unique blue and red uniforms.

The 79th New York fought in multiple Civil War battles such as Bull Run, Antietam, and Fort Wagner.

They were stationed in the Washington, D.C. area at multiple points during the war and fought a minor battle near Lewinsville Park in 1861, just a short distance from McLean, which may have influenced the school's choice of mascot.