Clark, 39, has been out of work since being sacked by after being sacked by Huddersfield in February.
But he is reported to have successfully gone through two rounds of interviews with cash-strapped Birmingham and is set to be named as Chris Hughton's successor.
Hughton left St Andrew's earlier this summer to become the new manager of Norwich following Paul Lambert's move to Aston Villa.
Birmingham, who reached the 2011/12 Championship play-offs, had also been linked with former Sunderland boss Roy Keane and ex-Charlton and West Ham manager Alan Curbishley.
Questions over a transfer budget and a possible exodus of players is rumoured to have put some candidates off the Birmingham job, with Jordan Mutch last week sold to Cardiff City.
But, according to Sky sources, Clark has decided he wants the role and he is set to be officially named in the next 24 hours.
As Birmingham manager, Clark would face former club Huddersfield in the Championship in the new season after the Galpharm club won promotion through the League One play-offs.
The Juventus jersey for the 2013/14 was released earlier this week. Be the first to wear the colors of the Old Lady.
Chelsea won the Europa League on Wednesday. The Blues defeated Benfica 2-1 on injury time goal from Ivanovic.
adidas has added some color to the Predator line with this new colorway. Released on May 17. Be the first to own a pair.
The Liverpool 2013/14 soccer jersey is available for pre-order. The Reds are eager to compete for silver next season.
The adidas Nitrocharge is the most talked about new cleat in years. It was released on May 15 and will take your pitch by storm.
One of the top soccer cleats for control the Nike CTR360 will not let you down on the field in tight spaces.
Ajax has released their away soccer jersey for the 2013/14 season. Get in the Gear.
Bayern Munich are kings of Germany and hope to be crowned kings of Europe at Wembley later this month!
The push for more color on their cleats, adidas has added the infrared colorway to the adiZero f50 Line.
The new PUMA evoSPEED 1.2 FG. A great new soccer cleat with classic look and first time for PUMA to be on the cleat.