The 21-year-old, who will cost the La Liga leaders an initial 75m euros plus another 11m euros (£9.5m) in variables, has agreed a five-year deal.

Netherlands international De Jong can also play in defence.

He was linked to many of Europe's top clubs including Manchester City, Juventus and Paris St-Germain.

De Jong joined Ajax from Willem II in 2015 and has played 65 times for the Amsterdam club, as well as winning five caps for his country.

He will see out the season with Ajax, who are two points below PSV Eindhoven at the top of the Dutch Eredivisie.

His new club's website calls him a "polyvalent player with an excellent reading of the game and ability to provide the killer pass".

De Jong will become the 20th Dutchman to play for Barcelona.