Guardian are reporting.
Spurs boss Andre Villas-Boas had already struck a deal to sign Holtby on a Bosman free transfer at the end of the season when his contract with the Bundesliga side expires.
The North London outfit were prepared to wait until the summer for the 22-year-old to arrive at White Hart Lane but an injury to Sandro left them short of midfield options.
After the Brazilian was ruled out for the remainder of the campaign following knee surgery, Villas-Boas moved to speed up the transfer and are believed to have persuaded Schalke to release the German international immediately for £1.25 million.
Tottenham were encouraged to move early for Holtby after it emerged the Gelsenkirchen club were willing to grant him an early release from the Vetlins-Arena and saw two bids rejected earlier in January before finally breaking through with their third to secure his immediate transfer.
Its believed he has signed a four-year deal and wants to setup his stall in London at the weekend, ruling him out of the game with Norwich City on Wednesday and Sunday’s clash with West Bromwich Albion.