Spain international Torres joined from Manchester City.
Spain international Torres joined Barcelona from Manchester City on a five-and-a-half-year contract, in a deal which is understood to be worth an initial £46.7million.
Torres, who has recovered from a broken a metatarsal sustained while on international duty in October, had hoped to make his debut in the Spanish Super Cup semi-final against Real Madrid on January 12.
However, that could be delayed after the club announced he tested positive for Covid-19 along with team-mate Pedri shortly after being presented at the Nou Camp.
Barca have been beset by financial difficulties in recent months, but were able to fund the Torres deal after securing a bank loan.
On Monday, the LaLiga club announced that by coming to a new agreement with French defender Umtiti, which will see some of his wages reduced, they had been able to officially complete Torres’ registration.
“Barcelona and first-team player Samuel Umtiti have reached an agreement to extend the latter’s contract until 30 June 2026. The French defender is reducing a part of the salary that he was due to receive in the year-and-a-half remaining on his contract,” a club statement read.
“This contract extension operation does not entail any greater financial commitments for FC Barcelona with regard to the player.
“FC Barcelona wishes to publicly express its gratitude to Samuel Umtiti for his willingness and the affection that he has demonstrated towards the club.
“Through this contract extension, FC Barcelona will be able to increase its ‘financial fair play’ quota and thus register Ferran Torres with the Spanish Professional Football League.”