Spurs agree early arrival of Holtby
"We are delighted to announce that we have reached agreement with Schalke for the immediate transfer of Lewis Holtby," the Premier League club said on their website on Monday.
Holtby, 22, was due to be out of contract at Schalke at the end of the season.
The versatile midfielder, who has three Germany caps, joined Schalke in 2009 from Alemannia Aachen and was loaned out to Bochum and Mainz prior to making his breakthrough with the Gelsenkirchen-based club.
Holtby, who captained the Germany Under-21 side but whose father is English, has made 160 appearances in his career and scored 29 goals.
His early arrival will boost Spurs boss Andre Villas-Boas after losing Brazilian midfielder Sandro to a knee injury for the rest of the season.
The North London side, dumped out of the FA Cup fourth round on Sunday at second tier Leeds United, are fourth in the Premier League as they eye England's fourth and final Champions League berth.
Schalke, sixth in the Bundesliga, face Turkey's Galatasaray in the Champions League last 16 in February and March.