The Croatia midfielder has signed a four-year deal with Julen Lopetegui's side.
According to Sport, Barca will receive a maximum fee of €8m ($9.6m) for the player depending, on whether Sevilla qualify for the Europa League or Champions League over the next two seasons.
New Barca head coach Ronald Koeman is said to have made it clear to Rakitic, who made 42 appearances in all competitions last season, that he would not be in his plans for 2020-21.
Negotiations stepped up on Monday, with Rakitic undergoing a medical after a fee was agreed between the clubs.
Rakitic was a fan favourite at Sevilla and captained them to Europa League glory in 2013-14 before signing for Barcelona.
🚨 LATEST NEWS | Agreement with Sevilla for the transfer of @IvanRakitic— FC Barcelona (@FCBarcelona) September 1, 2020
His first season at the club was a resounding success, the Catalans winning the treble under Luis Enrique, with Rakitic scoring the opening goal in the 3-1 Champions League final win over Juventus.
In total, Rakitic won 13 trophies with Barca, including four LaLiga titles and four Copas del Rey, and he was reportedly the subject of a €90m bid from Paris Saint-Germain in 2018.