The 21-year-old has put pen to paper on a six-and-a-half-year deal in North London, which will keep him at the club until 2030.
Dragusin, who is understood to have rejected offers from Bayern Munich and Napoli in favour of a move to Spurs, has been handed the number six shirt, most recently worn by Davinson Sanchez.
The Romania international could be in contention to make his debut for Ange Postecoglou’s side when they visit Manchester United on Saturday.
Dragusin initially joined Genoa on loan from Juventus in 2022, helping the club to earn promotion to Serie A and triggering clauses which turned that move into a permanent one.
The centre-back, who is also capable of playing at right-back, has made 22 appearances for Genoa across all competitions this season, scoring twice and assisting one more goal.
Nineteen of those outings have come in Serie A, with Genoa currently sitting 12th in the table in their first season back in the top flight.
Dragusin has also won 13 caps for Romania since making his debut for his country in March 2022.
The defender becomes Tottenham’s second signing of the January window, following the arrival of Timo Werner on loan from RB Leipzig on Tuesday.
It is also the second piece of business done between Spurs and Genoa on Thursday, after full-back Djed Spence moved in the opposite direction on loan.
