Kamil Zayatte has turned his loan deal with the Tigers into a permanent one.
Zayatte completes his move after the Tigers agreed a fee with Swiss side BSC Young Boys and the defender has signed a contract to keep him at the KC Stadium until 2012.
Hull City boss Phil Brown is delighted the deal has now been completed, saying:
"I think Kamil is somebody who has come into the Premier League and surprised everybody in the last six months.
"There are a lot of positives at the moment and hopefully there are more to come."