Benitez joined Birmingham for a club record £7.7million.
Benitez told City’s official website: “I’m very happy to be here. I know Birmingham City is a good club and since I have been in this country I have been really well received by the people at the club.
“I’m expecting a good season and I will try to do my best for the team and repay the confidence the club has shown in me.
“I know this is a good challenge for both me and the club and I’m really happy to be a part of it.
“I think this is the right time for Christian Benitez to play in the Premier League and I want to show the fans why Birmingham wanted to sign me.
“You never know when the right time is to come to the Premier League, but I take every challenge as it comes and I think I can show the Birmingham fans that I’m prepared to do a good job.
“I hope I can play my part in bringing back good times to the fans. I will try my best to help create and score as many goals as I can and sharing those moments is a special feeling.”