The 18-year-old defender has signed a three-year deal with the Catalan side with an option of a two-year extension.
Barcelona has put a release clause of €100 million in the left-back contract despite the total cost of his transfer being around €500,000.
Ndiaye happy to join Barcelona
After signing for Barcelona, the 18-year-old described the switch from Aspire Academy in Senegal to Camp Nou as an honour and privilege.
“An honour and great pride to join a club as prestigious as Barcelona, work continues,” Ndiaye said through his Instagram page.
Who is Moussa Ndiaye?
Ndiaye is a versatile player who can play in both the centre of defence and the flanks.
He helped Senegal to a second-place finish at the 2019 Africa U-20 Cup of Nations in Niger and he was named the Player of the Tournament.
Ndiaye also played a starring role at the 2019 Wafu Cup of Nations and was named the Man of the Match in the final game.
Senegal edged fellow West African side Ghana on penalties to win the regional title last October.
Ndiaye also made his mark in the Under-20s World Cup in Poland, where Senegal reached the quarter-finals before losing to South Korea on penalties.
Due to his outstanding performances on the international scene, Ndiaye was nominated for the 2019 Caf Youth Player of the Year award.
However, he lost to new Inter Milan signing Achraf Hakimi earlier this year.
Ndiaye joins compatriot Moussa Wague at Camp Nou, but he will team up with Barcelona B the club’s reserve team for the 2020-21 season.
Barcelona B also unveiled new goalkeeper Alex Ruiz on. The 19-year-old has signed for one season.
Meanwhile, Inaki Pena is expected to be promoted to the first team for next season.