The 31-year-old batter has previously captained Kent and also played for Hampshire, Yorkshire and Nottinghamshire.
Glamorgan have signed experienced batter Sam Northeast on a three-year deal.
With over 10,000 first-class runs and 25 centuries to his name, as well as strong records in white-ball cricket, he will be hoping to reinvigorate his career with the reigning 50-over champions.
Director of cricket Mark Wallace said: “Sam is one of the very best players in the county game and when we found out he was available we did everything we could to bring him to Wales.
“Signing Sam is fantastic news for everyone associated with the club and to attract a player of his quality is a good sign of the direction the club is heading in.
“He has a terrific record across all three formats and his versatility means he can bat in a number of different positions, while his experience will bring a lot to the changing room and help develop our younger players.”
Northeast, often rated as one of the best uncapped English players on the circuit, said: “I’m extremely excited for the challenge ahead at Glamorgan. Next year is the perfect time to build on the Royal London Cup success the club achieved this summer.
“I still have a lot of ambition in the game and I believe Glamorgan share that with me. Speaking to Mark Wallace and (head coach) Matt Maynard, I knew this was the right place for me to commit my future to.
“I am really looking forward to the next few years and the success we can have on the cricket pitch.”