The cost of the transfer is £125 million, equivalent to around 1.6 billion kronor, reports the BBC. The fee is joint first as the most expensive transfer in Premier League history - the same amount as when Swede Alexander Isak left Newcastle for Liverpool last year.
Fernández has signed a five-year contract.
"I couldn't be happier to be here, and I'm ready to take on the challenge of helping City continue to win titles," Fernández said, according to the club's website.
