A product of the Catalan giants' famed La Masia academy, the 22-year-old has agreed "to extend and improve his contract for a further two seasons up to 30 June 2031," the club said in a statement.
The contract will be signed in the coming days.
The industrious attacking midfielder has become an integral part of Barcelona's squad since making his debut in the 2023/24 season, making 113 appearances and scoring 29 goals.
He is also a regular in Spain squads and featured in the team's path to the EURO 2024 title.
He joins a list of key players, including teenage star Lamine Yamal, Raphinha, Gavi, Pedri and Pau Cubarsi, who have penned contract extensions in the past year.
Lopez will be aiming to send Hansi Flick's side four points clear at the top of LaLiga with a win at Elche on Saturday.