Rotherham have signed defender Danny Collins on a free transfer from Nottingham Forest.
MK Dons winger Daniel Powell has signed a new two-year contract at stadiummk.
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.