The Blades goalkeeper blundered when attempting to pass the ball out of defence with just eight minutes remaining.
Jack Clarke seized on the mistake, keeping his cool to roll the ball for Pablo Hernandez to tap into an empty net.
It was enough to settle an often scrappy derby clash in which neither side were able to reach the heights that have propelled the White Rose duo into the promotion race.
Up to his late mistake, Henderson had been in similarly impressive form to the 2-2 draw at the New York Stadium a week earlier.
He had made three excellent saves, while at the other end Bailey Peacock-Farrell was also in fine form.
A save apiece by the two goalkeepers had been the highlight of a first half that saw the Blades start strongly only for Leeds to grow into proceedings.
Bailey Peacock-Farrell, fresh from his penalty saving heroics in midweek, did brilliantly to turn a low drive from David McGoldrick round the post after the Blades striker had run from just inside his own half.
Leeds’ went closest through Aapo Halme, on for Liam Cooper. The young substitute latched on to a poor clearance from a Barry Douglas free-kick to thrash the ball goalwards only for Dean Henderson to save at full stretch.
Billy Sharp wasted perhaps the best opportunity of the opening 45 minutes when he headed over from a McGoldrick cross just before the break.
The second half continued in a similar vein with Mateusz Klich bringing a fine save from Henderson on the hour.
Three minutes later, Peacock-Farrell spared the blushes of Aapo Halme by keeping out McGoldrick after the young defender had made a hash of a clearance.
Enda Stevens fired narrowly over before Kemar Roofe headed wide from a Stuart Dallas cross before the derby was settled by Hernandez.