Sharp, just a few minutes after entering the fray, was on hand to head home a cross from fellow replacement Mirco Antenucci at the back post as Leeds were rewarded for a strong finish.
It helped ensure Leeds’ first win on the road since September 16 as they moved further clear of the relegation zone to extend their unbeaten league run to four matches.
In the process, it enabled Leeds to record their first double over Town since April 1939.
A lengthy stoppage followed the goal, with Tommy Smith knocked out in the lead-up to the strike - with the Town defender eventually stretchered off the pitch with an oxygen mask.
Smith was later taken to hospital by air ambulance, having been in and out of consicousness for ten minutes after sustaining a head injury, with Chris Powell hopeful he will make a recovery.
Sharp’s strike, just his third of the campaign, proved the decisive act in a hard-fought duel as Town suffered their third home league defeat in the tenure of Powell.
Sam Byram’s first goal since March 2013 put United ahead after just seven minutes, but Town restored parity on 28 minutes through substitute Harry Bunn’s seventh goal of the campaign.
Both sides made one change to their starting line-ups and both were significant ones.
For Town, Joe Murphy replaced the ill Alex Smithies in goal.
Meanwhile, Sol Bamba lined up for his debut for Leeds in place of the suspended Giuseppe Bellusci, for his first appearance in English football since April 2012, when he turned out for Leicester City in a 2-1 win at Elland Road.
The first shot in anger came from Town with a speculative long-ranger from Jacob Butterfield flashing not too far wide in the first minute before play switched to the other end with the rejuvenated Luke Murphy seeing his shot grasped by Town 'keeper Murphy.
Out of nothing, Leeds, afforded a dream start in the fixture at Town in October 2013, thanks to Matt Smith’s header, took the lead on seven minutes, again in front of the North Stand.
A perfectly chipped Murphy throughball caught Town napping, with Byram racing through and appearing getting the final touch under pressure from Jack Robinson after Joe Murphy had raced off the line - with the ball bouncing into the unguarded net.
Leeds, with Byram, Lewis Cook and Alex Mowatt doing the prompting, were sharper and slicker than the hosts in the opening exchanges, with Town suffering a blow on nine minutes when Nahki Wells limped off to be replaced by Bunn.
Slowly but surely, Town regathered their composure after the dual blow, although David Edgar was wayward with a shot when offered a chance 25 yards out, with his effort flying into the massed ranks of visiting Leeds supporters.
Vaughan then saw a shot deflected from a corner as Town cranked up the pressure and from the resultant flagkick, Chris Powell’s side restored parity.
Like with the opener, it was a soft concession with Butterfield’s corner latched onto at the back post by Bunn, with no-one challenging and Marco Silvestri rooted to his line, with the Town player entitled to hardly believe his luck as he headed home in comfort.
Town’s confidence was apparent and Vaughan soon saw a shot saved by Silvestri before Charlie Taylor was booked for a foul on Sean Scannell, making a belated impression and starting to pose problems.
Butterfield was then carded for a challenge on Byram before Vaughan beat Liam Cooper to set up a chance for Scannell, who turned Taylor and was inches wide with a low angled shot.
The half ended when Rudy Austin and Joel Lynch both picking up bookings following a contretemps.
Austin was lucky to escape a second caution after a challenge on Lynch early in the second period, with the midfielder giving the equivalent of a final warning.
Butterfield was also fortunate after not being penalised for an offence as well.
It was a half in which Town seized the initiative early on with their dangerous moment coming when Lynch headed off target following Butterfield’s corner.
At the other end, Leeds’s effort were somewhat token, with Mowatt firing over before the midfielder then hooked an effort off target after being set up by Cook.
Leeds made their first change just before the hour with top-scorer Mirco Antenucci replacing Mowatt.
A potentially big moment arrived on 63 minutes when Foy ignored appeals for a penalty after Byram went down in the box under pressure from Mark Hudson before keeper Murphy challenged Antenucci - but the Merseyside official was unmoved.
Chances were at the premium for most of the half, although Morison did well to clear a goalbound Bunn header following Butterfield’s corner.
A big opportunity arrived to Town with 15 minutes ago at the feet of Butterfield.
The midfielder danced past Cook on the left, with his cross-shot taking a deflection off Scott Wootton and flashing across the face of goal and just evading Scannell.
But in the final ten minutes, it was Leeds who finished the stronger.
A great chance fell the way of Antenucci after good play from Morison and Byram, but he showed a distinct lack of composure to blast over from ten yards out.
Moments later, a fine volley from Morison flashed wide before Leeds made the breakthrough with a predatory finish from Sharp, who headed home Antenucci’s cross, despite close attention from Murphy and Smith who collided.
A considerable stoppage followed with Smith receiving attention from medics before finally being stretchered off, to applause from all sides of the ground.
Town’s final chance fell to Scannell, who blazed over. But it was Leeds’s day.
Huddersfield Town: J Murphy, Smith (Lolley 90), Hudson, Lynch (Wallace 88), Robinson, Scannell, Edgar, Coady, Butterfield, Wells (Bunn 9), Vaughan.
Substitutes unused: Allinson, Dixon, Gobern, Majewski.
Leeds United: Silvestri, Wootton, Bamba, Cooper, C Taylor, Cook (Sharp 87), L Murphy, Byram, Austin, Mowatt (Antenucci 59), Morison.
Substitutes unused: S Taylor, Berardi, Bianchi, Montenegro, Sloth.
Referee: Chris Foy (Merseyside).