Caretaker manager Mike Phelan was indebted to his Hull players as they overcame off-field matters and an injury-hit squad to beat the reigning Premier League champions.
Robert Snodgrass' strike in the 57th minute grabbed all three points for the Tigers despite having only 13 fit senior players for the game and meant Leicester became the first Premier League champions to lose the opening game of their title defence.
Adama Diomande put Hull in front just before the break but Riyad Mahrez's penalty drew the Foxes level in the opening moments of the second half.
'I thought the players had it in them to produce something but all credit to the football players because they showed a lot of the determination,' Phelan told Sky Sports.