"It is the Mona Lisa of Mustangs," principal of Mecum Auctions Dana Mecum told The New York Times.
The car auctioned off at $3.4 million on the block, with a final sale price of $3.74 million after premiums.
The crowd cheered loudly when it hit $3 million.
The Mustang auctioned off for 25% higher than its original estimate, Mecum told the New York Times.
The car has a 390-cubic inch V8 engine with a four-speed transmission that gives it a 325 horsepower.
A 1968 Mustang with these same specs is worth about $70,000 in good condition without the special McQueen and "Bullitt" title, according to Hagerty Price Guide for collectible cars and CNN.
The production studio originally purchased two 1968 Mustang GT stunt cars for the film…
...but the other one was scrapped because of extensive damage.
"King of Cool" McQueen, who played a police lieutenant in the film, drove the Mustang during the film's famous car chase scene.
The film's 10 minute scene is considered the first car chase scene in modern film history, according to the auction house.
"In 1968, 'Bullitt' cemented itself as the pivotal moment in the history of car chase scenes, doing what none had ever done before and setting the standard for all that would follow, earning it the badge of honor that it carries today as the single greatest car chase scene in history," Mecum Auctions wrote in a statement.
McQueen was "particular" about the appearance of the car, according to the auction house.
Max Balchowsky, a friend of McQueen, modified the Mustang for the film.
The grille was painted black and scuffed to make it look more worn in for the film.
The engine and cylinder heads were also modified for "speed and sound."
McQueen dinged the left front fender during filming...
...and the fender still has the scars of the small accident, according to The New York Times.
Kiernan finished repairing and restoring the Mustang in 2008…
...but it was last revealed to the public in 2018.
Kiernan only made necessary changes and repairs...
...such as changing the carpet and front bumper.
The car still has the camera mounts welded into the vehicle from its days as a film star.
Its engine was rebuilt to how it was during its heyday.
The car also still has its original drivetrain, owners manual, registration card, and window sticker.
It also still retains its iconic factory Highland Green exterior color.
The steering wheel has a custom leather wrap...
...which matches the interior Black Deluxe color.
The Mustang has been registered as the 21st car in the National Historic Vehicle Register.
McQueen reportedly tried buying the car back in 1977 before his death in 1980, The New York Times reported.
However, the Kiernan family kept the car, despite McQueen's personal letter and request.
“It’s a car that was once thought lost to the passage of time, and with its reemergence, its unparalleled cultural significance has solidified it as a bona fide piece of pop-culture art and as an undeniable remnant of an incredible moment in movie and automotive history,” the auction house wrote.
The new owner's identity was not revealed.
