Torres passed a medical in Barcelona on Tuesday before putting pen to paper on a five-year contract with City.
City have agreed to pay Valencia an initial fee of £20.9 million for the 20-year-old, which could rise to £31.8 million depending on the player’s success at the Etihad Stadium.
Txiki Begiristain, the City director of football, moved quickly to tie up a deal for Torres after Leroy Sane left for Bayern Munich in a £55m deal last month.
“I am so happy to be joining City,” Torres said. “Every player wants to be involved in attacking teams and Manchester City are one of the most attacking in world football.”
Begiristain believes Torres has rich potential. “We have followed Ferran’s progress closely and have been very impressed,” he said.
“He is young and still developing, but his technical qualities are exactly what we are looking for in a winger.”
Torres is the first of what is expected to be a busy summer of arrivals at City as Guardiola rebuilds an ageing squad in an attempt to wrest back the Premier League title from Liverpool.
City have already had a £41m bid accepted by Bournemouth for Holland centre-half Ake, who is expected to undergo a medical and sign a contract once he returns from holiday in the days ahead.
Guardiola also wants to sign another central defender, 12 months after failing to replace Vincent Kompany, but the pursuit of Napoli’s Kalidou Koulibaly is far from straightforward. Relations with Napoli were strained by the collapse of a bid for Jorginho in 2018 and the Italian club’s £75m pricetag for a 29-year-old is considered excessive. Diego Carlos, of Sevilla, and Villarreal’s Pau Torres are also on City’s radar.
Guardiola would also love to sign the Bayern Munich left-back David Alaba, who can also play at centre-half, and would probably negate the need to sign a second central defender. However, Alaba, who has a year left on his contract at Bayern, is thought to favour a move to Spain and is coveted by a number of clubs.