The Baggies hosted QPR at The Hawthorns knowing a win would see them secure a return to English football’s top tier.
In the end, they had to settle for a point after playing out a 2-2 draw with Mark Warburton’s side.
But that didn’t matter after Barnsley toppled automatic promotion rivals Brentford to ensure it was Slaven Bilic’s side who finished as the Championship’s runners-up.
In what was a hugely anxious evening at The Hawthorns, QPR opened the scoring through Ryan Manning before goals from Grady Diangana and Callum Robinson put the Baggies on the brink of the Premier League.
But a spectacular Eberechi Eze strike pulled the visitors level to ensure Albion fans all over the world were left biting their fingernails.
In their end, though, Bilic’s team got over the line to secure a return to the Premier League after two years away.
Bilic rolled the dice for one of Albion’s biggest games in a generation with the boss making four changes and switching systems from the team that started the loss at Huddersfield.
For the first time since joining the club on loan, Callum Robinson was deployed up front instead of on the left-wing with both Charlie Austin and Hal Robson-Kanu on the bench.
Bilic also opted to make two changes to his back-line with Darnell Furlong and Kyle Bartley replacing Conor Townsend and Ahmed Hegazi.
Switching back to a 4-3-3 formation, Filip Krovinovic also earned a recall and came into the midfield alongside Romaine Sawyers and Jake Livermore.
Matheus Pereira started on the right wing and Grady Diangana on the left.
QPR included Bright Osayi-Samuel in their starting line-up, a player Albion are understood to be interested in signing.
The 22-year-old had been expected to miss out with the Hoops having accepted an offer of £5million from Club Brugge for his services.
But he lined up in a fluid front three alongside Ilias Chair here with West Ham target Eberechi Eze in a 4-3-3 formation.
In what proved to be an entertaining opening 20 minutes, both teams had spells where they looked bright on the ball.
It was Albion, though, who were creating chances with Bilic’s side relishing the space QPR were affording them.
They almost opened the scoring when Furlong whipped in a dangerous cross which Robinson turned wide with a glancing header.
Sawyers then saw a fierce low drive from 20-yards parried away by Joe Lumley while Pereira fired over inside the area after meeting a cut-back from Krovinovic.
After the drinks break, though, QPR started to find more intensity.
And they opened the scoring in the 35th minute when Manning let fly with an effort from 20-yards.
A combination of Livermore and Bartley saw that strike blocked. But the ball dropped kindly for the QPR man who, now unmarked, found the bottom corner from just outside the box.
The goal made a nervy Albion side look even more anxious.
But they hauled themselves back on terms just before the interval when a clever pass from Robinson found Diangana in the box.
The winger took a touch to take himself away from his marker and then arrowed a fierce low drive through the legs of Lumley and into the net.
Incredibly, the Baggies could have been ahead before the interval with Sam Johnstone playing a long pass towards Robinson which Yoann Barbet headed up instead of out.
That saw the ball break for the Sheffield United loanee who from just inside the box smashed a powerful volley narrowly wide.
Bilic’s side flew out the blocks following re-start and came a whisker away from taking the lead in the 48th minute.
Pereira danced into the box before lashing a powerful cross-come-shot that a stretching Robinson was just millimetres away from turning in at the back post.
Sixty-seconds later, though, there were ahead thanks to a goal scored by Robinson but that was made entirely by Diangana.
Despite both Luke Amos and Osman Kakay trying to tackle him on the touchline, Diangana squeezed through both of them before delivering the most wonderfully inviting cross.
And that was simply side-footed home by Robinson for his third Albion goal.
Just moments later the game should have been wrapped up when Pereira’s pass saw Robinson beat the offside trap and charge from one-on-one.
But despite looking destined to score, the Sheffield United loanee fired wide - with the miss seeing Bilic fall to his knees.
Perhaps that was because the Croatian knew what was about to come because on the hour QPR were level.
A crossfield ball found Eze who with his first touch not only controlled the ball but took it into the box.
But if that was exquisite his finish was even better with the midfielder then slamming the ball past Sam Johnstone and into the top corner.
Bilic made a couple of changes with 20 minutes remaining - with Chris Brunt and Charlie Austin replacing Sawyers and Diangana.
And just seconds later Albion were almost ahead with Krovinovic meeting a cross with a fierce strike from 10-yards only to be denied by an outstanding stop by Lumley.
With 10 minutes to go, Bilic switched Conor Townsend and Kamil Grosicki for Furlong and Pereira.
But it was at this point that news started to filter through that Barnsley were beating Brentford ensuring Albion were in touching distance of the Premier League with Bilic barking the scoreline at his players.
The final whistle then blew to eerie silence with Baggies players not sure if they got over the line and Albion’s staff all looking frantically at their phones.
Then eventually news filtered through that Barnsley had in fact won - promoting an eruption of noise and wild scenes of celebration on The Hawthorns pitch.
Albion (4-3-3): Johnstone, Furlong (Townsend 81), Ajayi, Bartley, O’Shea, Sawyers (Brunt 71), Livermore (Phillips 90), Krovinovic, Pereira (Grosicki 80), Diangana (Austin 71), Robinson.
Subs not used: Bond, Townsend, Hegazi, Robson-Kanu.
QPR (3-5-2): Lumley; Kakay (Shodipo 81), Masterson, Barbet; Manning, Ball, Cameron (Ramkilde 57), Amos, Osayi-Samuel (Kane 79), Eze, Chair
Subs: Kelly, Clarke, Oteh, Bettache, Gubbinse
Referee; Darren England