Ampadu, who turned 18 last week, joined the Blues from Exeter City last year and has made seven senior appearances.

Comfortable in both defence and midfield, Ampadu has also broken into the Wales side and won rave reviews from manager Ryan Giggs following his starring role in the 4-1 Nations League win over Republic of Ireland earlier this month.

"I'm really proud and happy," Ampadu said.

"I'm looking forward to the next five years and all I have got to do now is continue to work hard, and hopefully good things will happen."

Chelsea director Marina Granovskaia added: "Ethan has shown great potential and unbelievable maturity since arriving at Chelsea a year ago.

"In this short time he convinced a lot of people with his exceptional quality and mentality and we look forward to watching him develop into a key player for the club over the coming years."