Caldwell signs Black Cats deal
By Graeme Bailey
Last Updated: 01/01/70 1:00am
The 23-year-old has signed a three-year deal and is the first player to move between to the two clubs since Lee Clark in 1997.
"My focus is on getting Sunderland into the Premiership," said Caldwell.
"This is a big club and we want to get back into the Premier League where it belongs.
"I know the size of this club from living in the North East for so long.
"I'm delighted the move has finally gone through.
"I was very impressed when I met the manager and he is putting a good young team together.
"I enjoyed my time at Newcastle but I'm ready to move on and I'm really looking forward to the challenge ahead."
Caldwell is Sunderland's fifth signing of the summer after the arrivals of Carl Robinson, Stephen Elliott, Liam Lawrence and Dean Whitehead.