The winger was set to sign some time ago, but negotiations broke down as Tottenham wanted to restructure payments for the French U-21 international.
However, the clubs finally came to an agreement and Nkoudou is now officially a Spurs player.
The fee is understood to be around €13m, and the former Nantes player has signed a five-year deal at White Hart Lane.
"I can't wait to get to know the Premier League and the English game," Nkoudou told 'Spurs TV'.
"It suits my playing style, it's explosive. Everyone knows I'm fast, I like to dribble around players so the English league is best for me".