Bayern reportedly maintained contact with Ajax throughout the negotiations, but Barcelona ultimately convinced Dest they were the right club for his next stage of development.
The 19-year-old is one of several up-and-comers on the United States men's national team. Chelsea's Christian Pulisic, Borussia Dortmund's Gio Reyna, Juventus' Weston McKennie, and RB Leipzig's Tyler Adams are also competing in Europe's top five leagues.
Dest - born to a Dutch mother and Surinamese-American father - joined Ajax's famed academy at 12 years old in 2012. He made his competitive debut for the club in July 2019 and went on to make 36 appearances in all competitions in his first full season.
Dest is expected to earn significant minutes at the Camp Nou, with Sergi Roberto the only other senior right-back in Ronald Koeman's squad.
The talented defender has chosen to represent the United States over the Netherlands after playing for the Stars and Stripes at the under-17 and under-20 level.