The 18-year-old midfielder's new deal will run until 30 June 2026.
Pedri joined Barcelona from Las Palmas in August 2020 and played 53 times for them last season - the most of any player at the club.
He was also part of the Spain squad that reached the Euro 2020 semi-finals.
Spain boss Luis Enrique started him for each of his side's games at the tournament as he impressed on the international stage.
Pedri's exploits resulted in him being included in Uefa's team of the tournament.
