The Sheffield side, with just two defeats from their last 12 games, broke the deadlock in the seventh minute with the simplest of goals.
Midfielder Nick Montgomery played a short pass to David Cotterill and as Andy Dawson slipped, the ex-Wigan wideman picked out Halford at the far post who headed in from close range.
Hull, out for revenge after a 2-0 defeat at Bramall Lane in April, were almost level after winning a corner.
Dawson picked out Australia international Richard Garcia and the midfielder's strike from ten yards spun the wrong side of the bar.
Next Brazilian forward Geovanni's weaving run from midfield was halted on the edge of the United area.
Striker Caleb Folan almost found a way through as he chased a long ball downfield sweeping past centre-back Matt Kilgallon but Paddy Kenny spotted the danger and was quickly off his line to clear.
United captain Chris Morgan lasted just 31 minutes before being substituted with a recurrence of a hamstring problem and four minutes later Hull were level.
Zayatte first beat Sun Jihai to Dawson's curling free-kick and the ball flew past Kenny from five yards.
Garcia had a header blocked on the line by Kenny before Cotterill caught out Hull on the break, crossing quickly to sub Danny Webber whose header was deflected over the Hull bar.
Midfielder Bernard Mendy outpaced Gary Naysmith to hammer in a fierce strike which was blocked by Kenny at his near post.
Stephen Quinn has a chance to settle the issue eight minutes from time after neat work by Cotterill but dragged his shot wide.