The Catalan club confirmed the news on their Twitter page, with a mocked-up image of Dembele in a Barca shirt, and in a statement on their website they called him ‘one of the best on the continent’.
He arrives as a replacement up front for Neymar, who left for PSG earlier this month for a world record transfer fee. Dembele will wear the No 11 – vacated by the Brazilian’s departure.
The club confirmed the transfer fee is £96million plus add-ons, making Dembele the second most expensive player of all time, after Neymar cost the Ligue 1 side £198m.
If all of those add-ons are activated by individual and club successes, the fee will reach £136m.
It was also stressed in the club statement that Dembele’s release clause is €400m which is significantly higher than Neymar’s, which was triggered by PSG.
Barcelona say Dembele will arrive in the Spanish city on Sunday for a medical on Monday, with his official unveiling to be early next week.
The statement said:
‘Ousmane Dembele is one of the best young players in the world. The French winger stands out for his pace, ability to beat men and versatility.
‘He can play on either wing in attack and is known for his great dribbling. Last season he carried 103 successful dribbles, more than anyone else in the Bundesliga. Without doubt he is hugely talented player, one of the best on the continent.’
The player himself took to Twitter after the transfer was confirmed, proclaiming: ‘Visca Barca, Visca Catalunya!’, along with red and blue emojis.
The 20-year-old started his career in France with Rennes, before joining the Bundesliga side last summer and impressing immensely.
Dembele scored 10 goals in 49 matches, and created the third most assists in Europe, with 20 in all competitions.
It remains to be seen how this arrival influences Barcelona’s pursuit of Liverpool midfielder Philippe Coutinho, with Barcelona having made four bids, the last being £138m.
The 25-year-old has been absent with a back problem and illness amid speculation over a move, although he has still been called up by Brazil national team for their upcoming games.
Liverpool manager Jurgen Klopp said on Friday of the Coutinho situation:
‘In this moment he is on our injury list, that’s how it is and hasn’t changed.
‘I have no idea. I was not in contact so far with the Brazilian FA, but the rules are if they want to see and check him then he has to go there.’