Albion were beaten 2-0 at Sheffield United in the Sky Bet Championship on Wednesday night.
Second half goals from Sander Berge and Anel Ahmedhodzic were the difference, sealing the Blades’ promotion to the Premier League.
The Baggies remain two points off the top six with a couple of matches left and next up, Carlos Corberán’s side host Norwich City this Saturday (ko 5:30pm).
The boss made one change for the trip to Sheffield, with Taylor Gardner-Hickman replacing John Swift.
His team began well and could have opened the scoring inside two minutes – Jed Wallace crossing to Karlan Grant, but the forward unable to guide the ball home from close-range.
And it was Grant who tested Wes Foderingham for the first time soon after, a clever free-kick routine ending with his low shot pushed away. Replays showed Albion were unfortunate not to be given a penalty for the initial foul as Brandon Thomas-Asante appeared to get brought down inside the area.
Sheffield United dominated proceedings for a spell midway through the half without creating too many clear-cut chances, Jack Robinson the only one to test Alex Palmer via a volley.
Gardner-Hickman’s ambitious overhead kick provided the Baggies another opportunity, and even though he connected well it was comfortably gathered by Foderingham to ensure a goalless first period.
The Blades came out stronger following the interval and managed to go ahead just before the hour-mark, Berge converting from a few yards to take advantage of a defensive mis-hap.
Corberán turned to his bench and brought on Swift and Kyle Bartley in an attempt to salvage something.
Instead, though, United were the ones to score next – Ahmedhodzic diverting George Baldock’s volley past Palmer and doubling their advantage.
Albion tried to pull a goal back in the later stages, yet Foderingham comfortably stopped Gardner-Hickman and Brandon Thomas-Asante’s efforts.
And so it was Sheffield United celebrating come full-time, ruining the Baggies’ 5,000th league game and earning promotion back to the top flight.
Albion: Palmer; Furlong, Ajayi, Pieters (Bartley 71), Townsend; Molumby, Yokuslu (Swift 71) 71), Gardner-Hickman; Wallace (Malcolm 90), Thomas-Asante, Grant (Albrighton 78).
Substitutes: Griffiths, Livermore, Rogic.