Defender Curtis Davies has completed his move from Aston Villa to Birmingham for a fee believed to be £3.5m.
Davies joins midfielder Craig Gardner and defender Liam Ridgewell as former Villa players plying their trade across the city.
The former England Under-21 player had looked set to rejoin Leicester for a second loan spell but has instead opted for St Andrew's and another chance at Premier League football.
Birmingham's search for reinforcements up front also looks to be heading for a successful conclusion with Nigeria striker Obafemi Martins due to arrive for a medical on Sunday.
Former Newcastle forward Martins is close to joining Blues on a six-month loan spell from Russian side Rubin Kazan and will fly into the West Midlands this weekend.
Centre-half Davies, 25, has signed a three-and-a-half-year deal at St Andrew's and though he is not cup tied, he will be unavailable for tomorrow's FA Cup match at home to Coventry.
He is, however, cup-tied for the Carling Cup final later this month.
Earlier, Villa boss Gerard Houllier said: "He is on his way out to Birmingham. He had the option to go to Leicester or to Birmingham and he has opted for Birmingham. I think he is sold.
"He is a nice lad but, as you know, we have four centre-backs in James Collins, Richard Dunne, Carlos Cuellar and Ciaran Clark.
"He was not getting enough time to play. I understand that."
Davies has jumped at the chance of resurrecting his career at Barclays Premier League level.
He moved from West Brom to Villa in a £10 million switch four years ago after an initial loan spell.
His form when in partnership with Martin Laursen was good enough for him to be named in the senior England squad for the friendly international against Germany in Berlin in November 2008.
But Davies' form dipped after Laursen was forced to hang up his boots during the summer of 2009.
He slipped down the pecking order after the arrival of Dunne and Collins 18 months ago and in addition, Cuellar and Clark have moved ahead of him.
Blues boss Alex McLeish has been keen to sign a new centre-back once it became clear earlier this month Scott Dann would be out for the remainder of the campaign with a hamstring problem.
He has only three centre-backs now at his disposal in Roger Johnson, Martin Jiranek and Ridgewell, who has been operating primarily at left-back.
Davies will hope he can make the same impact as Ridgewell and Gardner who were only fringe players at Villa but have become key components of the current Blues side.
Gardner became a hero for City with the winner in the Carling Cup semi-final, second leg triumph over West Ham in midweek.
Davies was appointed West Brom skipper after his switch from Luton but angered Baggies fans when deciding to move to Villa.
Now he is looking to rebuild his career in the top flight.