An attack-minded left-back, the 23-year-old completed 37 take-ons and weighed in with five assists across 25 top flight games in France last season and even featured against his new employers in a Champions League round of 16 clash.
Pep Guardiola has welcomed another new signing to Manchester City.
Mendy quickly managed to establish himself as one of the best full-backs in world football with his powerful and direct style of play.
They have sold left-back Aleksandar Kolarov, 31, to Roma for £4.5m.
Israeli army prepares for protracted violence in West Bank
The latter remains inside the embassy, and Prime Minister Benjamin Netanyahu has vowed to bring him back to Israel. The Palestinian Ministry of Health said that one protester had been shot and killed on Saturday evening.
Guardiola was desperate to add Mendy to his full-back options after releasing Gael Clichy, Bacary Sagna and Pablo Zabaleta this summer, but City's original £44.5 million offer was rejected. "For such a young player, he has a wealth of top-level experience", the Spaniard said.
For Monaco, French global Mendy completed five assists in Ligue 1 and three in the Champions League last season, figures that suggest more goals should now flow from Guardiola's problem left side. So far, we've had no success.
As soon as the championship was over, I talked to my family and it was all clear in my head: I wanted to join Manchester City. Several clubs have been strongly linked with him including Premier League rivals Manchester City and French giants Paris Saint-Germain. "I'm sure he will prove a fantastic addition to the squad".
Last week City finally signed Walker, after months of negotiations, for a fee of £50m that could rise to £53m including add-ons.
Sky Bet make him, while it's also he joins PSG with City and Man Utd, Chelsea, Bayern Munich and Liverpool all priced at.