"We're sorry to see Luke go but he will feel the move allows him to build on a great start he's made to his career," said Cobblers boss Stuart Gray.
"We were not looking for Luke to leave but with his contract running out we did not have much choice. He obviously feels this move is for the best and we wish him well. We part on excellent terms and we wish him every success."
Chambers made 149 appearances for Northampton and was the club captain.