The 22-year-old joined Chelsea from Exeter City in the summer of 2017 but made just 12 first team appearances during his stay at Stamford Bridge.
Ampadu spent time on loan at RB Leipzig, Sheffield United, Venezia and Spezia while on Chelsea’s books but is sure to enjoy some stability at Leeds, who have paid £7m for the Wales international.
Ampadu is new Leeds manager Daniel Farke’s first summer signing as the Whites try to bounce straight back up following their relegation from the Premier League last season.
A statement from Chelsea read: "Ethan Ampadu has left Chelsea after completing a permanent transfer to Championship side Leeds United.
"The Welsh international arrived at Stamford Bridge from Exeter in 2017. He played 12 games in his first two years at the club, including three in the Europa League group stage on our way to victory in that competition against Arsenal in 2019. Ampadu was an unused substitute in Baku.
"He has accrued 44 caps for Wales and represented his country at Euro 2020 and last year’s World Cup.
"We would like to thank Ethan for his efforts throughout his time at Chelsea. We wish him all the best for the next stage of his career."
