Tchouameni has been a wanted man and the 22-year-old France international is understood to have turned down advances from Liverpool and Paris Saint-Germain.
The signing is a strategic one with a view to the future as the club is well aware that the midfield needs revitalising before it is too late.
While, like Camavinga, Tchouameni is viewed as a key piece for the future, he will also be expected to contribute straight away, as he is a full France international.
With the interest from other clubs, this is quite the coup for Los Blancos, who have landed one of the top-rated young players on the continent. Key to getting the deal done was the player's own desire to join Real Madrid, where Carlo Ancelotti - who even called the player - will be delighted to have him.