Fabrice Muamba has joined Birmingham permanently after spending last season on loan at the club from Arsenal.
Muamba was a key player in Birmingham's promotion season
The 19-year-old midfielder has signed a three-year-deal for an undisclosed fee and boss Steve Bruce said: "This is a great signing for us. I'm delighted."
Muamba, who made 41 appearances last season, told the Birmingham website: "The fans were probably the key reason why I have signed.
"I'm looking forward to the Premiership and am going to put myself about."
Bruce added: "I thought his performances towards the end of the season and the way he drove the team on was unbelievable for a young kid.
"He has got the attitude and athleticism to play in the Premiership and I'm sure he will only get better."
Arsenal manager Arsene Wenger wished Muamba well as he admitted the player may have found it tough to break into the Gunners first team next season.
"He is a highly-rated player but he has a lot of competition and he is in a position that if he comes back straight away it will be very hard for him to play," Wenger told Arsenal's website.