The 20-year-old, who joined Dortmund from Manchester City in 2020, has signed a seven-year deal at Stamford Bridge.

The England Under-21 forward scored 17 goals and contributed 14 assists in 107 games for the German club.

Chelsea have already signed Ipswich Town striker Liam Delap, Brighton & Hove Albion forward Joao Pedro, Sporting midfielder Dario Essugo and Strasbourg defender Mamadou Sarr this summer.

Gittens, who will not be able to play for the Blues until after the Club World Cup, said it is an "amazing feeling" to move to Chelsea.

"It feels great to join such a big club as Chelsea," he added.