City signed Fernandinho from Ukrainian champions Shakhtar Donetsk on Thursday as the Premier League runners-up begin an expensive overhaul of their squad.
City sealed their swoop for Fernandinho after he passed a medical at Manchester's Bridgewater Hospital.
The 28-year-old's signing is reported to have cost City £34-million, with another £22-million deal lined up for Sevilla winger Jesus Navas.
Fernandinho, who will wear the number 25 shirt, admitted he has already set his sights on helping City regain the Premier League title they lost to Manchester United this season.
"This is a change, a challenge and a chance that I have been waiting a long time for. Playing in the Premier League for City is like a dream," he told City's website.
"My ambition here is to win all the titles, the team here is strong, and so is the greatness of the club and the supporters.
"Professionally this is a spectacular thing. Playing for a huge club in a huge league makes me so happy. I hope I will be able to repay City for what they have done for me.
"I know I will face challenges but I am prepared for them. Every player at a high level faces pressure and must respond and I am ready for that too," he pointed out.
"I know a lot about City. Ever since they expressed an interest in me, I have been learning more."
Wealth of top-level experience
Fernandinho, who joined Shakhtar from Atletico Paranaense in 2005, will bring a wealth of top-level experience to City after appearing in the Champions League for the past eight seasons and winning the Ukrainian league title six times.
He also helped Shakhtar win the Uefa Cup in 2009 and scored the decisive goal against Chelsea in the Champions League this season.
He made his Brazil debut against Germany in 2011 and has five caps, but has yet to be called up by new Brazil boss Luiz Felipe Scolari.
Fernandinho's arrival will be followed by Sevilla winger Navas, whose club announced on Tuesday that they had accepted an offer from City.
City, who are still without a manager after Roberto Mancini's sacking last month, are expected to appoint Malaga's Manuel Pellegrini next week.
And after Mancini's complaints that City blew their chances of retaining the Premier League title by failing to secure his top transfer targets last years, it seems the club's Abu Dhabi-based owners are determined to ensure there is no repeat at the start of the Pellegrini reign.
Mancini was furious that Robin van Persie was allowed to join Manchester United from Arsenal, while he also missed out on Eden Hazard to Chelsea and failed to lure Daniele De Rossi from Roma.
The relationship between Mancini and his employers was never quite the same after that and City rarely hit the heights as they crashed out of the Champions League group stages and tamely surrendered the title to United.
But there has been a regime change at Eastlands in the last few months with player recruitment now being driven by new director of football Txiki Begiristain. – AFP