The 32-year-old has penned an 18-month deal at Molineux after moving for a fee of around £250,000.

The centre-back rejoins the club after his loan spell from October, where he played five times before being recalled by his parent club.

His arrival follows that of striker Joe Mason from Cardiff City last night in a £3million deal.

Wolves head coach Kenny Jackett still wants to add another forward to his squad before Monday's transfer deadline.

Williamson said: "When I left after the loan spell, I spoke to the gaffer and he expressed the desire to make it permanent and I told him that the feeling was mutual.

"I had a fantastic time here and I'm just glad it has been sorted out and I get back to playing.

"For me, it has been about getting fit as I've been injured and it can be difficult sorting out details when you are not playing and showing people what you can do.

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"I thoroughly enjoyed playing here and we had some good results. We just maybe needed to build on that and turn a few of the draws into wins.

"I loved my time here and that is why I am back here now."

Williamson hasn't recovered from a hamstring injury and is unlikely to be available for Tuesday's home game with Bolton. The defender, however, claims he is "not far away" from playing again.

He said: "It was frustrating to be called back and then get an injury but that is how it is – it's the nature of the game.

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"I'm not far off being back now and am looking forward to getting started and a new era. It will be easier coming back in having been before and I have already done all the initiation part.

"I can come in relaxed and ready to enjoy my football."

Kevin Thelwell, the club's head of development, added: "We were all massively impressed with Mike's loan spell and we feel he can make a significant contribution both on and off the field of play.

"We have got a young squad who will be able to draw substantially on his experience and we are confident he will be able to make us better.

"If you look at the statistics, we have got the youngest squad in the Championship and, by his very nature, the experience that Mike brings will automatically bring those other players along."