The winger becomes the fifth arrival of the Thomas Frank reign in north London after Spurs agreed a £55million deal with the Hammers.
Kudus had initially reported back for pre-season in east London, but the move materialised quickly and he now finds himself a new home in the capital.
The Ghanaian signed for West Ham back in 2023 from Ajax for £38m, and he made 32 appearances in the top flight last term, scoring five and assisting three times.
Kudus also becomes the first player since Scott Parker in 2011 to make the move from West Ham to Spurs.
Standard Sport previously reported that Kudus had an £85m release clause in his contract at the London Stadium for English clubs, although Tottenham have managed to negotiate the fee down.
Spurs were handed a boost when Ghana failed to qualify for the Africa Cup of Nations this winter, which means that they won’t lose Kudus mid-season, unlike many top clubs, who will be forced to let some of their star names depart to take part in the tournament.