The former Southampton loanee is the third defender to be brought into the Tottenham setup this summer.
The 26-year-old spent last season on loan at Southampton after one year helping Atletico Madrid win La Liga and reach the Champions League final, and with the Saints and the Spanish side disagreeing on whether the player should move to St Mary's permanently based on earlier negotiations, Tottenham stepped in and snapped up the player on a five-year deal.
The hashtag #WelcomeToby was introduced by the club, with fullback Kyle Walker a willing contributor to welcoming another Belgian to the club.
Fellow Belgian internationals Nacer Chadli and Jan Vertonghen also took to Twitter to make the defender feel at home, with the winger calling Alderweireld his 'mate' and welcoming the former Ajax man to the 'Spurs family'.
Alderwiereld's arrival means, including Moussa Dembele, the club now have four Belgium internationals on its books, as many as Belgian champions Anderlecht.
The player, who has 47 caps to his name for his country, is said to have cost in the region of £11.4 million according to the Guardian.