The Netherland's Vincent Janssen (R) takes on England's Chris Smalling in a friendly match.
Spurs paid £18.6 million ($24.4 million) for the transfer according to Sky Sports. If Janssen maintains the form he had at AZ Alkmaar - where he scored 27 goals last season - it will be money well spent.
But the deal had been a while coming - Janssen previously voiced his annoyance last month that AZ Alkmaar turned down a Tottenham bid of £15 million.
Janssen said at the time: "I have expressed my choice at the club. Tottenham Hotspur has made a high bid in my eyes. There has been an offer around €18m (£14.9m), but AZ will not even come to the table."
It seems the new amount was enough, however, and Spurs now has a very dangerous pair upfront in Janssen and England striker Harry Kane. Janssen is the club's second signing of the summer transfer window, the first being the £11 million signing of Southampton midfielder Victor Wanyama in June.
Tottenham very nearly won the Premier League last season, with the title in its grasp right up until the final week, but an astonishing run by massive outsiders Leicester City proved to be Spurs' undoing. The club eventually finished third, behind London rivals Arsenal.