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 Hull's website 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.
Hull boss Bruce has been busy in the transfer market since winning promotion to the Barclays Premier League, with today's double swoop taking the club's summer signings to 10.
Former Birmingham centre-half Curtis Davies, who came in for £2.25million, had been his most expensive addition prior to Huddlestone's signing, with a combination of free transfers, loan deals and cheaper arrivals such as Yannick Sagbo and Allan McGregor ensuring Bruce has operated well within budget.
Yet Bruce had made it clear that the midfield was an area which needed significant bolstering, especially since the departures of Corry Evans and Tom Cairney to Blackburn and a pre-season injury to Stephen Quinn.
Huddlestone certainly fits the bill as a player who can play as a midfield anchor who is also comfortable on the ball.
Sunderland were also on the lookout for such a player and Black Cats boss Paolo Di Canio had upped his interest in Huddlestone only to see Hull make a more decisive move this week.