Aurier moves to Spurs are competition for Kieran Trippier.
Tottenham sold Kyle Walker to Manchester City earlier this summer for £50m and they've now secured his replacement on Deadline Day.
"This is a huge and exciting opportunity at a massive football club and I am determined to prove myself," Aurier said.
The Ivory Coast international will wear the No.24 shirt and has signed a contract until 2022.
Aurier added: "This is a fresh start for me and I will do everything to make the Spurs fanbase, which is huge and diverse, proud of me.
"The fans are the most important people at any club and I am looking forward to showing them and everyone at Spurs the real Serge Aurier.”
Tottenham could also complete a deal for Fernando Llorente today.
The Swansea striker could be on the move for £12m.
Spanish footy expert Guillem Balague wrote on Twitter: "All done. @fernandollo (Fernando Llorente) is a Spurs player. 2 years (plus one) and around £12m.
"Llorente has been in London since this morning with Swansea's permission. Very good signing 4 Spurs. Impact player from bench 4 starters."
