Harrison has played a vital role in Leeds' upward trajectory in recent years, helping them win promotion from the Championship to retaining their Premier League status for the past two seasons.
Harrison had a series of loan spells at Elland Road from Manchester City before the move was made permanent in the summer of 2021.
The 26-year-old Englishman has made 197 appearances for Leeds in his time at the club, scoring 33 goals.
He has four goals and six assists in 27 Premier League appearances this season.
Leeds’ director of football Victor Orta said: “Jack is a crucial part of our squad and our plans going forwards and I’m really happy he has agreed to commit his long-term future to the club.
“He is one of the most professional players I have come across in my career, he has an unbelievable attitude and only wants to continue improving and I know we will see him at his peak over the duration of the next five years.”
Harrison nearly joined Leicester City in the January transfer window but the move broke down at the eleventh hour.
