The German has been a target of Frank Lampard for much of the summer, and a fee has finally been agreed, with Havertz signing a five-year deal at Stamford Bridge.
Lampard has been an admirer of the playmaker for much of the season, calling him a 'top player' as the Bundesliga season drew to a close.
Havertz joins fellow German international Timo Werner, Hakim Ziyech, Ben Chilwell and Thiago Silva as summer signings, taking Lampard's spending to well over the £200m mark for the season.
"I am very happy and proud to be here," Havertz said on Friday after the deal was confirmed.
"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!"