Dembele is due to arrive at Barcelona on Sunday to undergo a mecial after the La Liga giants agreed a mammoth £97million fee with Borussia Dortmund.
The France international has put pen to paper on a contract until 2022, which includes an astronomical £367m buy-out clause, and will be unveiled on Monday.
A club statement read: “FC Barcelona and Borussia Dortmund have reached an agreement for the transfer of Ousmane Dembele for €105million plus add-ons.
“The player will sign a five-year contract and his buy out-clause is set at €400million.
“Dembele will arrive in Barcelona on Sunday and he will undergo a medical on Monday morning local time.
“Shortly, more details of the running order of the player’s presentation on Monday will be available.”
Barcelona have been in the market for a new forward following the loss of Neymar ealier this month, when the Brazilian left for a world-record £200m move to Paris Saint-Germain.
Dembele, who joined Dortmund for just £13m a little over a year ago, has become the second most expensive player in the world following Neymar’s £200m move from Barca to Paris Saint-Germain.
And the 20-year-old, who bagged 10 goals and set up another 21 last season, will take Neymar’s No 11 shirt at the Nou Camp.