Lewis Hall will spend next season on loan at Crystal Palace after agreeing a new contract at Chelsea which could run until 2030.
The 18-year-old has signed a new six-year deal, with the option for a further year, after an exceptional first 12 senior appearances at Stamford Bridge.
The Blues have held off interest from Premier League rivals including Newcastle and agreed to send the youngster to south London on his first loan move.
Roy Hodgson's friendship with Mauricio Pochettino was a major factor in Palace winning the race.
Hall is not expected to be registered in time to make his debut on Saturday away at Sheffield United.
The teenager will primarily play in central midfield at Selhurst Park but has played the majority of his senior minutes at Chelsea as a left-back.
He may, however, initially replace injured England international Tyrick Mitchell at full-back before playing a more permanent midfield role.
Chelsea were open to giving Hall a chance to stay and deputise for Chilwell this season but have struggled to sell Marc Cucurella.
Cucurella is keen to fight for his place after his £62million move from Brighton one year ago.
Hall has been at Chelsea since he was eight years old and made his debut for the club at just 17 under former manager Thomas Tuchel in early 2022.
