The 30-year-old defender has moved to the KC Stadium for an undisclosed fee, having spent just under a decade at White Hart Lane
The defender leaves Spurs on an undisclosed fee, with the north Londoners keen to stress that he will "always be welcome" at White Hart Lane.
"I have been here for almost a decade and have loved every minute of it," Dawson told Tottenham's official website.
"I would like to say thank you to everyone at the club, including the supporters.
"We have enjoyed some incredible moments together and I hope the club continues to move forward in the future."
Spurs chairman Daniel Levy added: "Michael has been an outstanding club representative both on and off the field.
"He has always given everything for the Spurs shirt - just one of the reasons he is so deservedly popular throughout the club."
Dawson, now 30, made 236 Premier League appearances for Tottenham after joining the club from Nottingham Forest in January 2005.