The France worldwide put pen to paper on the five-year deal on Monday after agreeing terms in the past week.
Barca have not yet revealed how much Umtiti's new release clause will be but a source told ESPN FC it will be "significantly more" than the current €60m.
The French defender was reportedly a transfer target for Manchester United, but has agreed a new five-year contract with the LaLiga giants.
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Umtiti recently fuelled even more speculation linking with the Premier League runners-up by refusing to rule out a move, insisting he would only make a final decision on his future after the World Cup. "I never saw myself in another team".
"I just said the word 'joker.' I don't know how that word is interpreted [in Spain], but you can interpret it as you wish". With the city and the team, I've earned everyone's trust.
"This club has been in my heart since I was a kid, and it is a dream to play here with players like (Lionel) Messi".
In that time, he has won one La Liga title as well as two Copas del Rey.
Umtiti is now on global duty with France as they prepare for the 2018 World Cup.