Dean Ryan, Gloucester's head coach, said that Lloyd would add experience and versatility to the side: "Leon is a tremendously gifted and adaptable player and someone we are thrilled to have in our squad.
"He will offer a significant attacking threat, is powerful, strong and has an excellent try-scoring record at the highest levels. Having played in 50 Heineken Cup matches, his experience alongside our younger backs will be invaluable."
Lloyd, at 6ft 4in and 15 stone, made his breakthrough at Leicester in the 1996/97 season, featuring as a 19-year-old in the Heineken Cup final defeat to Brive.
His form and try-scoring threat marked him out as one of the game's rising stars and he was included in England's 1999 World Cup squad. Lloyd made his international debut a year later and was Leicester's hero with two tries in the 2001 Heineken Cup final win over Stade Francais.
This season he made 11 Guinness Premiership appearances, bringing his total number of appearances in the league for Leicester to 144 with 33 tries.
Lloyd told www.gloucesterrugby.co.uk: "Leicester is a fantastic rugby club and I am very fortunate to be able to say I was involved in one of the most successful periods in their history, particularly this season in winning the double.
"I owe a tremendous debt of gratitude to many different people for what I have been able to achieve and it is something I will never forget. To have spent 10 years at one club has been a privilege and honour and their support throughout has been wonderful.
"But now I have the opportunity to experience a new culture at a club who are trying to create their own period of history in the English game.
"It is a brilliant challenge and the way Dean Ryan has recruited for next season and beyond, it is clear to me Gloucester are going in a hugely exciting direction and that is something I really want to be a part of."