Kakuta spent last season on loan at Rayo Vallecano in La Liga where he made 35 appearances, scoring five goals.
But he found first-team opportunities at Stamford Bridge harder to come by, playing just 16 games for Chelsea from 2009, five of which were starts.??
???We thank Gael for his service and wish him well for the future,??? a club statement read.
Kakuta moved to Stamford Bridge from Lens in 2007 and enjoyed a fine first season at the club, finishing as top scorer for the youth team and being named Academy Scholar of the Year.
He made his first team debut in November 2009, coming on as a second-half substitute in a home game against Wolverhampton Wanderers, and featured 12 times during the 2010/11 campaign as Chelsea finished runners-up to Manchester United.
Loan spells with Fulham and Bolton Wanderers followed, before the winger moved to Europe, enjoying productive periods with Dijon and Vitesse Arnhem.