Last season, Rudiger had 26 appearances for AS Roma in Serie A with 2 assists, playing as a right-back.
In the international level, Rudiger made his debut for the German national team. Until now, he has made 17 caps for Germany, with the recent devotion to winning the 2017 FIFA Confederations Cup.
“It’s a great feeling because not every player has the opportunity to join a huge club like this, Rudiger said.
“I am looking forward to meeting up with my new team-mates and I’m very proud to officially become a Chelsea player.”