The West Londoners have been the busiest of the Premier League clubs in this summer’s transfer window having been previously banned from signing players for two transfer windows.
Havertz became Chelsea’s seventh summer arrival after Germany team-mate Timo Werner, Hakim Ziyech, Ben Chilwell, Thiago Silva, Malang Sarr and Xavier Mbuyamba.
"I am very happy and proud to be here," Havertz said. "For me it is a dream come true to play in a big club like Chelsea and I can't wait to meet all the players and the trainers. Yeah, I am very happy to be here!"
He added: “I read very much messages from them (Chelsea fans) they write very often on my social media accounts so I saw it and I can’t wait to play in front of the fans”
Havert has revealed he cannot wait to learn from Frank Lampard as he thinks the former midfielder can help him improve.
The Germany international added: “Lampard was very offensive like me. He loved to score goals and I love to score goals as well. I think he will help me a lot in my position and the things I can improve. I can’t wait to work with him.”
Chelsea director Marina Granovskaia labeled Havertz as one of the best young footballers in the world and insists the club is happy to have secured his services.
She said: "Kai is one of the best players of his age in world football, so we are very happy that his future lies at Chelsea.
"He has proven pedigree in one of the best leagues in Europe, he plays for the German national side and he is an exciting, dynamic talent.
"We are delighted to be able to add his versatility and quality to the squad before the season begins."
