A goal from Robbie Brady just past the hour mark gave the visitors the win, helping Hull's promotion hopes as well as damaging those of Reading.
The hosts created the first chance after just three minutes when Simon Church got on the end of Michail Anotonio's cross, only to send his header narrowly wide.
Hull's first sight of goal came through a Robbie Brady free-kick that tested Adam Federici.
Reading came close with a pair of set-pieces themselves shortly after. First, Kaspars Gorkss headed wide from an Ian Harte delivery, before Alex Pearce almost broke the deadlock.
Harte found Pearce at the back post, and his first effort was cleared off the line before havoc ensued in the penalty area. Hull eventually hacked the ball clear, leaving Reading wondering how they hadn't taken the lead.
Shaun Cummings was presented with a good chance at the start of the second half, but he blazed his shot over the crossbar.
Despite this pressure, it was the Tigers who took the lead. A ball over the top found Brady, who was onside, despite the protests of the Reading defence. Brady made no mistake, slotting the ball past Federici to give his side the lead.
The Royals pushed for an equaliser but were continually frustrated by a stubborn display from the visitors, who held out to record a valuable victory.