Villa agreed the deal with Sevilla last week.
The 29-year-old is Villa's third summer signing already already following the acquisitions of Boubacar Kamara on a free transfer from Olympique Marseille and the permanent signing of Philippe Coutinho from Barcelona following a loan spell.
Aston Villa have parted with £26m for Carlos' signature as Steven Gerrard's side make efforts to improve on a 14th place finish last season.
Carlos came close to joining Newcastle United in the January transfer window but the two sides could not reach an agreement over the transfer fee.
Carlos joined Sevilla from Nantes in the summer of 2019 and won the Europa League in his first season at the club.
He was part of the Brazil under-23 team who won gold at the Tokyo 2020 Olympic games.
"I am really happy because the Premier League is one of the best competitions," Carlos said after the transfer was confirmed.
"I always want to do the best for the club and the shirt I'm wearing. Even now I can't believe I'm here because it's a dream to compete in the Premier League. And now I have a very clear opportunity, I hope to give it 100% my best, and to be able to play to the best of my ability."
