James, 25, will move to Sandy Park from the Cardiff Blues after agreeing a two-year deal with the Chiefs.
"Signing for Exeter Chiefs is a great move for me," said James, who has 10 Wales caps. "They are a team that I've watched come up to the Premiership over the last few years and do really well."
He went on: "I've had a fantastic seven years with the Blues and I am very grateful to have been given the opportunity to play for them and for the support I've been shown over my career.
"There are many highlights I've had, including winning the EDF Energy and Amlin Challenge Cups, but I felt the time was right for a fresh challenge.
"Exeter are clearly an ambitious club and having talked to the coaches about where they want to go and also the plans for the stadium, I felt I wanted to be a part of it all and experience something different."
- Sports & Recreation
- Exeter Chiefs
- Cardiff Blues