Davies has penned a three-year deal with Hull and joins for an undisclosed fee.
He said: "I'm delighted to be here.
"I feel that I'm joining Hull City at an exciting time and the chance to play in the Barclays Premier League was also a huge attraction. It's something that I've been lucky enough to do before and I wanted to get back to that level.
"Hopefully I can help this team to have a good season and push as high up the table as possible. I can't wait for Chelsea on the first day of the season now."