GRAHAM Dorrans ensured the already-promoted Baggies finished the season on a high with a last-gasp equaliser to extend Albion's unbeaten run to 12 games.
The freescoring hosts looked like enduring a frustrating afternoon in front of goal as they failed to polish off several chances.
The Tykes came within seconds of pulling off a smash-and-grab raid thanks to Hugo Colace's goal on the hour-mark.
But newly-crowned Albion Player-of-the-Year Dorrans notched the equaliser with virtually the last kick of the game - his 18th strike of a stunning season - to spark wild post-match celebrations.
Roberto Di Matteo named an unchanged side for the fourth successive match.
There was one change on the bench, though, where Ishmael Miller, back from illness, replaced Academy ace Sam Mantom.
Mark Robins made three changes as Martin Devaney, Carl Dickinson and Ryan Shotton came in for Stephen Foster, Luke Potter and Adam Hammill.
Former Albion great Darren Moore was given a hero's welcome pre-match by the home hordes as he captained the visitors.
There was a real party atmosphere inside The Hawthorns as the fans packed out the stadium to salute their promotion heroes.
In keeping with tradition, this final game of the season proved an open affair and the Tykes threatened after just three minutes when Devaney teed up Jacob Butterfield, who fired just wide form 15 yards.
Albion soon began stroking the ball around in their usual confident manner and Jonas Olsson wasn't too far away with a header from Dorrans' corner.
Chris Brunt then jinked inside Nathan Doyle before curling a vicious right-footed shot just wide of former Albion keeper Luke Steele's left-hand post.
The Baggies were thankful for two vital blocks by Steven Reid in the tenth minute to prevent Iain Hume and Butterfield troubling Scott Carson's goal.
Bednar soon fashioned two decent shooting opportunities for himself in the box but was well off target on each occasion.
As the game suffered a lull in goalmouth action, the supporters amused themselves with the odd Mexican wave.
The next moment of any note did not arrive until the 35th minute when Reid and Simon Cox got in each other's way as they attempted to convert Dorrans' corner, which had been flicked on by Bednar, from two yards.
Albion's hopes of finding a breakthrough were not being helped by a Barnsley side who had opted to go back into their shell and defend deep after their early ambition.
But the Baggies had the Tykes at sixes and sevens on 38 when Dorrans combined brilliantly with Bednar to set up Brunt, who fired horribly wide from six yards at the back stick.
Barnsley finally ventured into the Albion half again a minute later when Hume drilled a long-range effort just over.
Di Matteo rang a change at half-time as Joe Mattock replaced Marek Cech at left-back.
Albion started the second 45 very much on the front foot but struggled to get any change out of Barnsley's Moore-inspired rearguard action.
In fact, it was the Tykes who recorded the first shot of the half, although Hume was well off target from 30 yards.
Di Matteo made another switch on 53, with James Morrison coming on for Cox.
Bednar was presented with a half chance when Shotton completely missed Gabriel Tamas' raking ball from the back. With Moore in tow, the Czech international advanced into the box before firing horribly wide when he would have been better served squaring to the unmarked Dorrans.
The impressive Reid was equally off target with a speculative 25-yard drive.
But Albion fell behind on the hour mark. They went to sleep at a Butterfield free-kick and the unmarked Colace tapped home at the far post.
In the same minute, Steele had to pull off the save of the game when he somehow tipped over Robert Koren's 20-yard exocet following a trademark cut in from the right.
Di Matteo made his final throw of the dice two minutes later as Miller replaced Reid.
Moments later, Brunt failed to trouble Steele with a 25-yard free-kick.
Albion were piling forward but Olsson was unable to get enough purchase on a near-post flick with his right boot to seriously test Steele from Dorrans' corner.
On 74, Olsson threatened again, this time from a Brunt flag-kick, but volleyed over.
Steele had another comfortable save a minute later when he smothered Miller's 20-yard grass-cutter.
Albion's agony continued when Koren directed an instinctive header just wide after Olsson had headed Brunt's corner goalwards.
Koren failed to hit the target with another gilt-edged chance on 81 when he screwed wide from 12 yards after Dorrans had helped on Bednar's centre.
With Albion pressing for an equaliser, they were susceptible to the counter-attack and Mattock did well to block Jon Macken's header from Devaney's left-wing cross.
But the Baggies were soon back on the attack and Miller teed up Koren, who fired just over from 15 yards.
Barnsley sub Luke Potter then blocked Miller's shot and there was more agony for the Albion striker when Bednar's threatening cross into the six-yard box just evaded his outstretched boot.
But Albion's insatiable desire to finish the season on an unbeaten note finally brought its reward in the second minute of stoppage time.
Bednar whipped another dangerous low cross into the box and Dorrans coolly guided home his 18th of the season from 12 yards.
ALBION (4-5-1): Carson; S Reid (Miller 62), Tamas, Olsson, Cech (Mattock HT); Koren, Cox (Morrison 53), Mulumbu, Dorrans, Brunt; Bednar. Subs not used: Kiely (gk), Barnes, Wood, Meite.
BARNSLEY (4-5-1): Steele; Hassell, Shotton, Moore (Potter 78), Dickinson; Hume, Doyle, Butterfield, Colace, Devaney; Macken. Subs not used: Preece (gk), Kozluk, Foster, Adam, Gray, Taylor.
GOALS: ALBION - Dorrans (90+2). BARNSLEY - Colace (60).
BOOKINGS: ALBION - Dorrans (removing shirt 90+2).
REFEREE: M Oliver (Northumberland).
ALBION STARMAN: Robert Koren.