Francis Jeffers scored his first goal for the Club as Jim Magilton's side achieved Town's best away win in eight years in sensational style at the KC Stadium.
The recent loan signing from Blackburn levelled the scores for Blues midway through the first-half after Dean Windass had put Hull in front.
Jaime Peters will claim Blues' second goal just before the break, his shot deflecting in off Sam Ricketts.
Alan Lee made it 3-1 early in the second-half after good work by Jeffers and Jason De Vos extended the lead on 62 minutes following poor defending in the Hull box from David Wright's free-kick.
Substitute Danny Haynes sent the travelling Blue Army into party mood with a brilliant finish 10 minutes from time before Windass scored his second of the game from the penalty spot.
The victory was Town's first away win in eight games with the Jeffers' strike the first in that run and his first League goal in two years.
The former Everton striker partnered Lee in attack, Jon Walters dropping to the bench as Town began the game looking for a first win at the Yorkshire club.
Stuart Elliott wasted a great chance to give Hull the lead inside the first minute but the Northern Ireland international blasted over the bar from 10 yards. Damien Delaney then fired wide as the home side started brightly.
Sylvain Legwinski had Town's first opening but couldn't keep his shot down from 12 yards while at the other end, Ray Parlour had the same result after former Blue Nicky Forster had set him up.
Hull took the lead on 22 minutes, Ricketts' cross was headed against the bar by Elliott and Windass was in the right place to tap the rebound over the line.
Blues responded immediately, Jeffers taking a long ball in his stride and despite stumbling in the Tigers' box he kept his composure to slide the ball past Boaz Myhill.
Gary Roberts was booked for a foul on Elliott, his eighth yellow card of the season, Windass then testing Lewis Price with a header after good work by Forster.
Dean Marney shot over for the home side, while Lee got on the end of a Dan Harding cross to carve out an opening for Jeffers, his shot blocked by Danny Coles.
Town were not to be denied though and again Jeffers was central to the plot, twisting and turning on the edge of the box before finding Roberts who set up Peters, the Canada international's shot going into the net off Ricketts.
Hull could have been level before the break though, again Forster the provider, cutting in from the left and setting up Windass who blasted his shot wide from a great position.
Town extended the lead four minutes after interval, Jeffers again involved to ease the ball on to Lee who showed strength and pace to work his way into the box and shoot across Myhill into the far corner.
Windass flashed a header wide from a Parlour corner but it was Town that threatened at every opportunity, Myhill denying Lee with a burst off his line.
Delaney was booked for a foul on Lee before Blues made it four, Wright's free-kick deflecting into De Vos' path and the skipper gratefully put the ball in the empty net from three yards.
Former Hull frontman Walters replaced Jeffers a minute later and Town continued to sweep through the Hull defence at will, Owen Garvan denied by Myhill.
Danny Haynes joined the action for the last 20 minutes, Peters making way and the striker was soon in the action, almost getting on the end of a Roberts' cross.
Ashbee then brought down Lee as the Republic of Ireland international prepared to let fly from 18 yards, Wright sending a free-kick straight into the wall.
Haynes then made it five with a bullet strike nine minutes from time before Hull had the chance to reduce the arrears from the penalty spot, Garvan bringing down Jon Welsh, Windass scoring from the spot.
Haynes, Walters and Legwinski all had chances to add to Town's scoresheet as the Blue Army rose to salute a performance that took Blues to halfway in the Championship table with the biggest away win since the 6-0 victory at Swindon in April 1999.
Town: Price, Wright, De Vos, Bruce, Harding, Peters (Haynes 72), Garvan, Legwinski, Roberts, Lee (Richards 80), Jeffers (Walters 63). Subs not used: Supple, O'Callaghan. Booked: Roberts.




















