The Ghana international joins City after they agreed to pay the £65m buyout clause in his Bournemouth contract. He has penned a deal to 2031.
Viana said this morning: “Antoine is a really exciting signing for the football club.
“He made it clear to us immediately that it was City he wanted to join. His enthusiasm for this football club has been clear throughout the process.
“He has huge quality. Two great feet, pace, power, a habit of influencing games and, importantly, real room for growth and development. I am excited to see the player Antoine can become in the weeks, months and years ahead.
“We are constantly watching players all over the world. Antoine was the one we most wanted. He has shown he can perform in the Premier League. He is humble, hard-working, professional and totally focused on being a better footballer. He is ideal for us.”