Manchester City would be interested in signing Raheem Sterling if he were to become available, according to Sky sources.
Tottenham have completed a deal for Cologne defender Kevin Wimmer and he will join them in June, Sky sources understand.
The Denmark international joins Romania defender Vlad Chiriches and Argentina forward Erik Lamela in signing for the club on a busy day.
"We are delighted to announce that we have reached agreement with Ajax for the transfer of Christian Eriksen," Spurs said on their official website.
Eriksen added: "Everyone has followed the development of Spurs and it's something I want to be part of."
The 21-year-old has already represented his national team on 37 occasions, scoring four goals, and was a key player for Ajax, having moved there from Odense in 2008.
He made 161 appearances and helped the Amsterdam side win three successive Eredivisie titles from 2011, and signs for a Tottenham side that bolstered their ranks immeasurably on Friday.
Chiriches became the club's fifth summer purchase on Friday morning when he completed his £8.5million move from Steaua Bucharest and four hours later, Tottenham confirmed that they had signed 21-year-old Lamela for fee thought to be around £25.8million.
The purchase of Eriksen on Friday evening is likely to take their summer spending to over £100million in this transfer window and paves the way for Gareth Bale to join Real Madrid in a world-record move.