Northampton Saints will sign Cornish Pirates scrum-half Tom Kessell for the 2015-16 season.
The 25-year-old has meanwhile signed a short-term deal with Bristol, but will be loaned back to fellow Championship side Pirates.
He has made over 100 senior appearances for the Penzance-based club since 2011.
"We believe that he has the potential to perform in the Premiership and in Europe," said Saints director of rugby Jim Mallinder.
Kessell will remain with the Pirates until the end-of-season Championship play-offs, at which point he will play for Bristol.
He will be competing with England's Lee Dickson and Samoa's Kahn Fotuali'i for the number nine shirt at Franklin's Gardens.
"Joining the Saints is a fantastic opportunity for me," Kessell said.
"I'm really looking forward to working with the calibre of players that the club's already got. Hopefully I'll be able to develop as a work in progress, take any opportunity that I can get, and be the best that I can."