The Blues disclosed this in a statement on their website on Thursday.
The statement read, “Academy midfielder Lewis Bate has today completed a permanent transfer to Leeds United.
“We thank Lewis for his time at the club and wish him well in the future.”
Bate, 18, first started training at Chelsea at the age of eight.
The midfielder captained Chelsea’s Under-18s in the FA Youth Cup final last year.
Bate also featured three times for Chelsea’s development squad during their title-winning Premier League 2 campaign.
He has been named among the substitutes for Chelsea senior men’s team on three occasions, most recently for in their FA Cup fifth-round tie against Barnsley in February.
