The centre joined Tigers Academy at under-16 level from Oakham School and gained representative honours with England at Under-18 and Under-21 level while making 42 first-team appearances for Tigers following his debut against Newcastle Falcons in October 2004.
I have had a great experience during my time at Leicester but it is the right time to move on and I am looking forward to a new challenge at Exeter, said 23-year-old Cornwell.
Exeter are an ambitious club with excellent facilities and I hope to help them towards their aim of taking Premiership rugby there.
I hope to have the opportunity to play against Tigers in the not-too-distant future!
Cornwell captained Leicesters Guinness A League championship-winning team in 2006 and led the senior team for the first time in the EDF Energy Cup during 2006/07. He made his final Tigers appearance as captain in the match against the Classic All Blacks at the end of last season.
Captain of England Under-21s when they won a Six Nations Grand Slam in 2006 and at the Junior World Cup in 2006, Cornwell will maintain his links with the Matt Hampson Trust after tireless service for the cause since his teammates injury in 2005.
Ive had a great time at Leicester, he said. On a personal note, Id like to thank everyone for their support in my time at the club, not just for me but also their great support of the Matt Hampson Trust.