The North London club announced on Friday that a deal with Ajax had been agreed and Sanchez had signed a six-year contract, subject to a medical and work permit.
Spurs are confident there will be no problems with the work permit.
The Colombian told Tottenham's website on Friday, "I would like to thank the coach, management, players and fans of Ajax. It is a great move for me to come here to develop my career."
"I am very excited to be signing for such a famous club as Tottenham Hotspur. I am looking forward to working with Mauricio Pochettino and the players and meeting everyone there."