It ends their eight-year stay in the top flight.
Manager Darren Moore had overseen three wins and two draws in his five games in caretaker charge of West Brom, and their relegation was confirmed just hours after he was named April’s Premier League Manager of the Month.
He took over from Alan Pardew, who left the club bottom of the league following just one win in 17 matches in what has been a disastrous campaign at The Hawthorns on and off the pitch.
Moore is the fourth manager the club has had this season, after Tony Pulis, Gary Megson and Pardew.
Dropping out of the Premier League also has a huge financial impact.
Deloitte Sports Business Group estimates relegation to cost West Brom approximately £50m in Premier League distributions alone.
Premier League clubs receive roughly a £90m share from the league each season, from money generated through TV revenues from domestic and foreign markets.
While relegated teams receive a £40m parachute payment, there is still a large shortfall for clubs to make up.
Those parachute payments equate to 55% of the broadcast revenues in the first year after relegation.
In year two it goes down to 45% (£35m) and then to 20% (£15m) in year three.
However, if a club has only been in the Premier League for one season – like Brighton or Huddersfield – they would only receive the first two payments of the parachute money.
As well as the reduced TV revenues, relegated Premier League clubs will also suffer financially in matchday revenue and incomes associated with that, such as hospitality.
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Commercial deals with sponsors could take a hit, too.
So while the parachute payments are sometimes perceived to give relegated Premier League clubs a head start on their new Championship rivals, they will certainly still feel the financial hit of relegation.