Alli has made a huge impact since completing his £5million move from MK Dons last summer, scoring five goals in 18 Barclays Premier League appearances.
The 19-year-old has also broken into the senior England set-up and scored his first international goal in the 2-0 victory over France in November.
"We're delighted to announce that @Dele_Alli has signed a new contract with the club which will run until 2021," Tottenham posted on their official Twitter account.
Source : PA
Source: PA