In a move that angered West Bromwich Albion, where he had been on the books since he was just six-years-old, the Catalan giants unveiled the 16-year-old with the blaugrana shirt and announced him as their latest addition.
A statement on the club's official Twitter account said: "Louie Barry has joined FC Barcelona".
Barca are excited by Barry's potential.
Camp Nou giants Braca confirmed that Barry, who celebrated his birthday in June, had put pen to paper after passing a medical.
The 16-year-old turned down a professional contract with the Midlands club and was also on the radar of Paris Saint-Germain.
But it is Barça who have secured his signing and on Thursday made the announcement of the player who will now be part of the Juvenil A side having signed a three-year contract.
Ex-West Brom teammate Marvin Rodgers has joined Manchester City, while Liverpool have edged out Europe's elite in their bid to sign Fulham's Harvey Elliott.