Kriralok Desk: The 21-year-old forward returns to Spain in a £46.3m deal just 18 months after leaving Valencia to join City.
Barcelona will pay £8.4m in add-ons and must sell some players to comply with La Liga financial regulations.
The club is able to fund the deal despite its current financial troubles thanks to a recent bank loan.
City manager Pep Guardiola confirmed the move was imminent on Thursday and said he is happy for Torres.
Spain international Torres has made 43 appearances and scored 16 goals for City since joining from Valencia in August 2020.
He started City’s opening six matches of the season but was dropped to the bench for the goalless draw against Southampton in September and has not featured at all since suffering a foot injury on international duty with Spain the following month.
City’s director of football Txiki Begiristain said: “Ferran should be proud of what he has achieved here at Manchester City.
“Last season was his first time in a new country, but he adapted well. He always gave 100%, worked hard for the team and scored goals which helped us win trophies. We wish him all the best at Barcelona and for the rest of his career.”
Torres told Guardiola he wanted to leave in order to secure more regular first-team football and City feel they have strong depth in forward positions, with Bernardo Silva, Jack Grealish, Riyad Mahrez, Raheem Sterling, Gabriel Jesus and Phil Foden providing competition for a starting spot at Etihad Stadium.
Barcelona are short on forward players after their financial issues meant they were unable to keep hold of Argentine superstar Lionel Messi, and allowed Antoine Griezmann to rejoin Atletico Madrid over the summer.
Former City striker Sergio Aguero joined Barca, but was forced to retire from football earlier this month aged 33 because of a heart condition.
Manager Roanld Koeman was sacked in October with the club ninth in La Liga after collecting just 15 points from their opening 10 games.
He was replaced last month by club legend Xavi, who has won three of his first eight matches in charge in all competitions so far, but could not stop Barca exiting the Champions League after the group stage.