Bentaleb played only 13 times for Spurs last season because of injuries.
The 21-year-old midfielder has not trained with the Tottenham first-team since July after being told he was not in manager Mauricio Pochettino's plans.
"He is 100% fit but we must give him time to integrate into the team," Schalke director Christian Heidel said.
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Algeria international Nabil Bentaleb has joined German side Schalke 04 on a season-long loan from English Premier League side Tottenham.