For the first time in second-tier history, the 90 minutes ended goalless and penalties were required to separate the two sides following a cagey affair.
The Terriers, who squandered the two major chances of the match early on, held their nerve to win the shootout 4-3 and earn promotion to the Premier League for the first time in their history.
Reading are left to rue what could have been, meanwhile, falling short in the playoffs for a joint-record fifth time after what was a nervy performance over the 120 minutes from both sides.
Huddersfield created their two killer chances of a tight match in the opening 15 minutes, neither of which they could make the most of.
The Chelsea loanee remained onside but did not see the ball until late, perhaps explaining how he placed the ball wide of goal from just a couple of yards out - one of the great playoff misses.
A lively start to the match did not offer a true reflection of what was to follow, with the teams - separated by just four points at the end of the regular season - cancelling each other out all over the field.
The only other sight of goal for either side in the first half arrived midway through when Lewis Grabban, on the winning side with Norwich City here two years ago, curled wide from range after working some space.
Chris Lowe and John Swift fired in the first on-target attempts of the afternoon in quick succession early in the second half, the latter of which forced a good stop out of semi-final hero Danny Ward.
It was proving to be a playoff final devoid of any major chances, bar the two created by Town early on, with substitute Collin Quaner slotting wide 12 minutes from time when Nakhi Wells was better positioned behind him.
Huddersfield won 22 of their 25 regular-season fixtures by a one-goal margin and still held out hope of snatching the match at the death in front of the 76,682 spectators at Wembley Stadium.
It was Reading captain Gunter who came closest to finding a breakthrough in seven minutes of added time, though, heading over the bar from a decent Garath McCleary delivery.
Having won three of their last four playoff finals, the latter two via penalties following a goalless 120 minutes, Town knew full well that their dream of playing top-flight football was still alive.
McCleary blasted well wide with one shot and come closer with a second at the end of the first period of extra time, latching on to Liam Kelly's ball but not putting enough on his attempt to get the better of Ward.
The only other chance fell the way of Wells, who turned inside the area and placed the ball wide of Ali Al-Habsi's goal to signal the dreaded penalties.
Reading had lost three of their last five shootouts in all competitions and that negative stat was extended on a gloomy day in the capital.
Moore and Swift both missed from the spot, after Hefele had initially been denied to give the Royals the advantage, sealing a fairytale achievement for David Wagner's unfancied Terriers.