Steve Bruce's men were unable to secure the three points against the champions which would have guaranteed them second spot, yet they had a helping hand from Yorkshire rivals Leeds who beat third-placed Watford 2-1.
Former Hull loanee Fraizer Campbell had threatened to derail the Tigers' hopes by breaking the deadlock just after half-time, but two goals in five minutes through Nick Proschwitz and Paul McShane looked to have turned Hull's entire season back around. Andrew Taylor was then sent off for Cardiff before Nicky Maynard levelled from the spot.
Watford's automatic promotion dream turned into a nightmare after losing goalkeeper Jonathan Bond to a horror injury.
Bond was taken to hospital after a sickening collision while the Hornets could not take advantage of Hull's late slip-up.
The Bluebirds' last-gasp penalty equaliser against second-placed Hull raised the roof at Vicarage Road, where there were still some 10 minutes to play following the lengthy treatment required by Bond.
But Watford, who had also lost striker Troy Deeney to a red card, could not find the goal which would have taken them up.
Instead, Ross McCormack broke away down the other end and grabbed a late winner for Leeds. Almen Abdi had earlier cancelled out Dominic Poleon's opener.