The United States international joined Milan from Chelsea in 2023 after previously playing for Borussia Dortmund and has established himself as an important figure at the San Siro.
The 28-year-old has scored 44 goals in 141 appearances for the Italian giants, finishing as the club's leading scorer during the 2024-25 season.
Milan said the new agreement reflected a shared desire to build on the progress made since Pulisic's arrival.
"Pulisic's contract extension reflects a shared commitment to building on the progress made together in recent years, with the ambition to keep improving, achieve new milestones and write more memorable chapters in the Club's history," the club said in a statement.
Pulisic has also enjoyed considerable success on the international stage, representing the United States at two World Cups.
He is a four-time winner of the US Soccer Male Player of the Year award and remains one of the country's most recognisable footballers.