The 28-year old centre-back has joined the Tigers on a three-year deal for an undisclosed fee, believed to be in the region of £2.25million.
"I'm delighted to be here," Davies told the club's official website.
"I feel that I'm joining Hull City at an exciting time and the chance to play in the 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."