The 28-year-old has signed a five-year deal with City and will join his brother Kolo at Eastlands.
The highly-rated midfielder joins City in a deal worth around £27.5million.
“This is another fantastic signing for Manchester City, and I am very pleased Yaya has joined us, he is a very good player,” City boss Roberto Mancini told the club’s official website.
“Everyone knows Yaya is a player that we have admired for a long time, and we would like to welcome him to Manchester City.
“He has played at the top level with Barcelona and I am sure his experience and ability will be very important for us.”
