Nkunku, who has won 10 caps for France, is manager Mauricio Pochettino's first signing since he took charge in May.

"I am incredibly happy to be joining Chelsea. A big effort was made to bring me to the club. I am very excited for this challenge and will be proud to wear the Chelsea shirt," Nkunku said.

"Having played in Ligue 1 and the Bundesliga, I now want to play in the Premier League, one of the strongest leagues in the world.

"I am looking forward to meeting my new coach and team-mates and showing the Chelsea supporters what I can do on the pitch."

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Nkunku, whose Chelsea contract starts on 1 July, won three Ligue 1 titles and two French Cups during four years at Paris St-Germain before joining Leipzig in 2019.

He was named Bundesliga player of the season and German PFA player of the season in 2021-22 after scoring 20 goals and contributing 15 assists in the league.

Nkunku scored in the final of the German Cup this month as Leipzig won the competition for the second successive year. They finished third in the Bundesliga last season.

Nkunku made his France debut last year but missed the World Cup campaign because of a leg injury.

Laurence Stewart and Paul Winstanley, Chelsea's co-sporting directors, said: "Christopher has proved himself one of the standout attacking players in European football over the past two seasons and will add quality, creativity and versatility to our squad."