Caulker has started 24 games for Tottenham in all competitions this season.
Villas-Boas admitted: "This club has great expectations towards Steven's future.
"I think for a first season back at Tottenham the amount of games he has played shows the quality that he has.
"Plus this involvement with England means we have a great central defender for the future.
"Here, like any other top club, he competes against the best central defenders in the world as we have and he will continue to do so."