The 23-year-old defender signed a five-year contract which will expire by the year 2024.
Hernandez was among the France squad that won the 2018 FIFA World Cup, beating Croatia 4-2 in the final.
Speaking about the move, Hernandez said: “This is a really important day in my footballing career. FC Bayern Munich is one of the best clubs in Europe and the world. I’m proud to be able to fight for all possible titles with Bayern. I’d like to thank Atletico, the management, the coaches, my teammates and the fans for 12 wonderful years. Atletico will always remain a part of me. Now I’m looking forward to taking the next step with FC Bayern.”
Bayern sporting director, Hasan Salihamidzic added: “I’m very happy we’ve been able to sign one of the best defenders in the world, a World Cup winner, in Lucas Hernandez,”
“Lucas can play both in central defence and at left-back. Moreover, Lucas will continue our great tradition of French footballers and improve our team.”
Hernandez will join Bayern Munich from Atletico Madrid on 1 July 2019 when the summer transfer window will be opened.