The centre-half moves to the KC Stadium on a three-year contract after both clubs confirmed the deal was completed via their official Twitter accounts.
The 30-year-old, who was club captain at White Hart Lane, made 324 appearances for Spurs but has been deemed surplus to requirements by new manager Mauricio Pochettino.
"I have been here for almost a decade and have loved every minute of it," Dawson, who has four England caps, told the Spurs website.
"We have enjoyed some incredible moments together and I hope the club continues to move forward in the future."
Dawson will bolster the Hull defence with the club looking to overturn a 1-0 deficit in the second leg of their Europa League playoff against Belgian side KSC Lokeren on Thursday.
- Sports & Recreation
- Michael Dawson
- Tottenham Hotspur