The Brazilian midfielder is the newly-promoted side's second summer signing after Joao Palhinha joined from Sporting Lisbon.
Pereira has signed a four-year contract with the option to extend for a further year at Craven Cottage.
The 26-year-old spent over a decade at Manchester United, having joined the club's academy as a teenager before graduating to the first team.
Pereira never established himself as a first team regular at Old Trafford, making 75 appearances in total for the first team and spending time on loan at Granada, Lazio and Flamengo last season.
Following the official announcement on Monday, Pereira told Fulham's club website: "I'm very happy to be here and I can't wait to start the season with Fulham. I want to help Fulham as much as I can to be where they belong.
"Marco Silva was very important for this. I spoke a lot with him, and he was a key factor in me being here."
Fulham vice chairman and director of football operations, Tony Khan, added: “It’s a tremendous pleasure to welcome Andreas Pereira to Fulham! Andreas is a very talented player, and he’s excited to join Fulham and work with our great coach Marco Silva. We believe that Andreas will be a valuable asset for the club."
Fulham will begin their 2022/2023 season against Liverpool.
