Leicester came close to opening the scoring early on as Danny Coles brought down Elvis Hammond on the edge of the box and Danny Tiatto took the resulting free-kick which deflected off the wall and then onto and over the bar for a corner.
Another chance fell to Hammond late in the first half and Tiatto fired the ball across goal from the left and Boaz Myhill attempted to collect it, but he spilled the ball in front of Hammond but he could only blaze the ball over from five yards.
Hull's only real chance came in stoppage time in the first half and they made the most of it as David Livermore cleared the ball into Fagan from the left and he managed to swivel and strike the ball right-footed into the top corner from ten yards to put the home side ahead.
Leicester came back into it in the second half and equalised on 55 minutes as Williams whipped in a corner and Kisnorbo rose to head the ball towards goal with Myhill only managing to palm the ball off into the back of the net.
Leicester then took the lead on 68 minutes as sub Matt Fryatt played the ball into Williams on the edge of the area, who curled the ball into the net from 20 yards with a great right-footed effort.
It got worse for Hull on 72 minutes as Coles brought down Fryatt midway in the Hull half and was adjudged to be the last man by the referee, resulting in a red card for the Tigers man.
Sub Jon Parkin had a chance to equalise soon after coming on, but he fired his shot from 12 yards straight at Foxes keeper Paul Henderson.