World Cup winner Mike Catt is to join London Irish at the start of next season.
Bath have not offered the versatile South African-born back a new contract.
The 32-year-old, who has been capped 62 times by England and played for the British and Irish Lions on their tour to Australia in 2001, has played 227 games and scored 64 tries for Bath since joining them in 1992.
"I am really excited about playing at London Irish," said Catt.
"The club has a good squad and is strengthening it. After 12 enjoyable years with Bath, the change will be a challenge, one I am really looking forward to."
London Irish managing director Conor O'Shea said: "This is one of the most exciting signings this club has made in recent times.
"Mike will add an extra dimension to our squad and to the backs in particular. His participation in and experience of the England squad will benefit London Irish.
"We are delighted he is joining us in July."
The Exiles recently announced the signing of Robbie Russell, the Scotland hooker, from Saracens.