The Barclays Premier League new boys have agreed a three-year deal for 26-year-old Huddlestone, who arrives from White Hart Lane for an undisclosed fee.
Fellow midfielder Livermore, 23, has joined the Tigers on a season-long loan.
A statement on club website hullcityafc.net read: "The Tigers are delighted to confirm the signing of England international midfielder Tom Huddlestone from Tottenham Hotspur.
"We are also pleased to announce the loan signing of Tottenham midfielder Jake Livermore."
Huddlestone, capped four times by England, has been allocated squad number eight for the new season, which for Steve Bruce's men gets under way at Chelsea on Sunday.
The club did not disclose the fee agreed for Huddlestone or if it represents a new record buy, but it's understood the fee at least matches their £5million record signing of Jimmy Bullard.
Livermore made 11 Premier League appearances for Spurs last season and has had spells on loan at Leeds and Ipswich among others.
Huddlestone, who made 209 appearances for Spurs in eight years since signing from Derby, admitted Bruce's vision for Hull's return to the top flight was crucial in persuading him to sign on.
"It's obviously very exciting times for the club, but for myself personally it's been a frustrating couple of years at Tottenham whether it be [because of] injuries or team selection. Hopefully I can come here, cement my place in the starting 11, and do well for the club," he told Tigers Player.
"I know a few of the lads here already and they've only said good things about the manager and the club as a whole.
"I had a chance to speak to Steve Bruce and I liked his ideas, his role for me within the team, and what he wants the team to do and the way he wants them to play.
"Once I'd spoken to him my mind was made up really."
He added that "a few teams" had been vying for his signature but indicated that only Hull had matched Spurs' valuation.
"There was a few teams interested and obviously Tottenham accepted the bid," he said.
"It was a very difficult decision [to leave Spurs]. Having been at Tottenham for eight years and with the club in the situation they are now, it was a very difficult decision to make, but one based on footballing reasons.
"With the club accepting the bid, then I kind of knew where I stood."
Despite arriving so late in pre-season, Huddlestone is ready to be thrown into the mix at Stamford Bridge this weekend.
"I'll be ready to train tomorrow and then we'll see what the manager does for the game," he said.
"They don't really come much bigger than Chelsea away, with Jose Mourinho returning and everything else that goes with it."
Sunderland Premier League Fixtures
Saturday August 17
15:00 Premier League Sunderland v Fulham
Saturday August 24
15:00 Premier League Southampton v Sunderland
Saturday August 31
17:30 Premier League Crystal Palace v Sunderland
Saturday September 14
15:00 Premier League Sunderland v Arsenal
Saturday September 21
15:00 Premier League West Brom v Sunderland