The Croatia international will fill the void left by Cesc Fabregas at Camp Nou, with youngster Denis Suarez moving to Ramon Sanchez Pizjuan on a two-year loan.
Rakitic, who is currently in Brazil on World Cup duty, will fill the void left by Cesc Fabregas, who last week departed Camp Nou to sign for Chelsea.
Barcelona has also confirmed that former Manchester City youngster Denis Suarez will move to Ramon Sanchez Pizjuan on a two-year loan as part of the agreement.
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Rakitic joined Sevilla from Schalke for 2.5 million euros in January 2011 and gradually established a reputation as one of the finest young playmakers in Europe, eventually being made club captain.
The 26-year-old made 59 appearances in his three seasons with the Andalusians, scoring 15 goals, and led the club to glory in the Europa League last season.