Roger Johnson has conceded Birmingham's relegation from the Barclays Premier League was a key factor in him wanting to leave St Andrew's.
The central defender held talks with Wolves officials at Molineux on Monday morning before undergoing a medical over a ?7million deal.
Wolves boss Mick McCarthy has been pursuing Johnson throughout the summer and has stepped up his efforts after losing out to Leicester in the race to sign Matt Mills from Reading.
Johnson said: 'We're half-way there. It wasn't an easy decision. I enjoyed my time at Birmingham but relegation half made the decision for me.
'I want to be in the Premier League and I'm sure everyone can appreciate that. But I enjoyed my time at Birmingham.'
Eye on the ball: Johnson joined Birmingham two years ago
City had initially been hoping to secure around ?10 million for Johnson. But a compromise has been reached between the two clubs.
Lifelong Chelsea fan Johnson moved from Cardiff to Birmingham in a ?5m deal two years ago.
He quickly adjusted to the top flight and formed an effective partnership with Scott Dann, another Championship player with Coventry.
Johnson set for Wolves switch after ?7m fee agreed with BirminghamBirmingham confirm Stoke's ?16m double swoop for Dann and Jerome