The France worldwide put pen to paper on the five-year deal on Monday after agreeing terms in the past week.
The Cameroon-born France international's new deal ties him to the LaLiga champions until 2023, and he put pen to paper in an official ceremony at the Nou Camp on Monday morning.
"Barcelona and the player Samuel Umtiti have reached an agreement for the renewal of a contract that will bind both parties for the next five seasons", Barca signalled in a statement released on Sunday.
Barcelona president Josep Maria Bartomeu is confident that rival clubs will steer clear of making an approach for Samuel Umtiti due to the size of his release clause.More news: Where is Melania Trump? Mystery as public absence extends to 22 days
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That relatively low release clause had seen him linked with a move away, with Manchester United and Manchester City mentioned.
Umtiti signed for the Catalan giants from Lyon in the summer of 2016, before that year's Euros, for a now ridiculous cheap €25 million.
"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".
"I am really happy here and I have everyone's confidence, so I couldn't leave". That's why I'm not going to leave.
Umtiti can now focus on performing well for France at the World Cup, where he will be Les Bleus' first-choice centre-back.