The result extended the Baggies' winless run to nine matches across all competitions, including eight in the Championship to leave them in the relegation zone after 13 games.
Bruce departs The Hawthorns with West Brom sitting two points adrift of safety, with Under-21s coach Richard Beale taking the reins on an interim basis while the club searches for a permanent new boss.
"West Bromwich Albion have today parted company with manager Steve Bruce," read a statement on the club's official website.
"Backroom staff Steve Agnew, Stephen Clemence and Alex Bruce have also left The Hawthorns. The club would like to place on record its thanks to Steve Bruce and his coaching staff for their efforts since arriving in February.
"Under-21s coach Richard Beale will oversee first-team affairs on an interim basis, assisted by James Morrison and Gary Walsh. The process of recruiting a new manager is now under way and an appointment will be confirmed in due course."
Former Birmingham City boss Bruce was only appointed in February of this year, overseeing 32 matches with West Brom but winning just eight of those.
Bruce leaves with a win percentage of just 25% - his lowest win percentage from any of his 12 managerial spells at a club in a career spanning more than 1,000 games.
Sparta Rotterdam 
AZ Alkmaar 
Southampton 
Liverpool 
Como 
Fiorentina 
Sevilla 
Rayo Vallecano 
Ajax 
Pec Zwolle 
Palermo 
Sampdoria 
Ipswich 
Manchester Utd 
Napoli 
Roma 
Moreirense 
FC Porto 
Leganes 
Real Madrid 
Lazio 
Bologna 
Empoli 
Udinese 
CSKA Moscow 
Rubin 
Slovan Bratislava 
AC Milan 
Sparta Praha 
Atletico Madrid 
Valencia 
Barcelona 
Stade Brestois 29 
Bayer Leverkusen 
Red Bull Salzburg 
Bayern Munich 
Paris Saint Germain 
Inter 
RB Leipzig 
Manchester City 
Feyenoord 
Sporting CP 
Arsenal 
FC Rostov 
Spartak Moscow 
Aston Villa 
Juventus 
Celtic 
Club Brugge 
Dinamo Zagreb 
Borussia Dortmund 
Monaco 
Benfica 
PSV 
Shakhtar Donetsk 
Lokomotiv Moscow 
Dinamo Moscow