The Denmark international has joined Spurs in a deal believed to be worth around £11.5million.
The club revealed on Twitter: “We are delighted to announce that we have reached agreement with Ajax for the transfer of Christian Eriksen.”
Eriksen was named Dutch Football Talent of the Year and Ajax Talent of the Year in 2011 and has long been linked with moves to some of Europe’s biggest clubs.
Eriksen said: “Everyone has followed the development of Spurs and it’s something I want to be part of.”