Darius Vassell's superb early strike gave Leicester a third away win of the season as the Foxes leapfrogged Hull in the Championship table.
The former England striker crashed in a fine volley from Richie Wellens' cross after 11 minutes.
Hull offered little in response, and their task got harder when Liam Rosenior was sent off for a foul on Greg Cunningham in the second half.
Hull's Paul McShane later had a goal ruled out as the visitors held on.
Vassell, tempted back to English football by Leicester manager Sven-Goran Eriksson in November after a spell with Turkish side Ankaragucu, had already got an early sight of goal when he fired wide in the third minute.
But the 30-year-old made no mistake eight minutes later when he met Wellens' cross with an excellent volley that flew past debutant Hull keeper Bradley Guzan.
The Foxes could have had more before the break, with Paul Gallagher firing a good chance wide and Lloyd Dyer getting round the back only to snatch at his shot.
The Tigers looked distinctly out of sorts, their best chance coming when Cameron Stewart's shot was blocked by Chris Weale.
Leicester continued to look the more likely to find the net in the second half, with Gallagher driving wide from 20 yards.
Hull's cause was not helped when Rosenior was shown a red card for a foul on Cunningham just after the hour mark.
The tackle was late, rather than malicious, but teenage defender Cunningham had to be given oxygen and stretchered off with a broken leg.
The Tigers did have the ball in the net through McShane in the 72nd minute but the referee blew up for a foul on Weale.
Leicester could have had a second when Gallagher swung in a free-kick from the right but Vassell shot too close to Guzan.
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