The Baggies took an early lead when Martin Olsson could only divert Gareth McAuley’s header into his own net.
Despite Blackburn dominating long periods of the second-half, Marc-Antoine Fortune and Liam Ridgewell scored to make sure of the points for West Brom who move 11 points clear of the relegation zone with six games to play.
Anthony Modeste was sent off late on after lashing out at Billy Jones to complete a miserable day for Rovers.
West Brom made three changes from the side which lost 2-0 at Everton last weekend, with Youssouf Mulumbu, Graham Dorrans and Fortune coming in for Paul Scharner, Somen Tchoyi and Shane Long. For Blackburn, David Dunn came in for Marcus Olsson in Steve Kean’s only change from Monday’s 2-0 defeat at Manchester United.
West Brom dominated the early proceedings, winning a succession of corners before forcing the opener after eight minutes.
Chris Brunt’s corner from the right was headed towards goal by McAuley, and in trying to clear, Martin Olsson could only shank the ball into his own net.
West Brom continued to enjoy the better of the play without really testing Paul Robinson in the Rovers goal.
Scott Dann got a free header on Bradley Orr’s right-wing cross but it was straight at Ben Foster. A header either side of the goalkeeper would have been a far greater source of concern for Foster.
Fortune brushed Steven N'Zonzi off the ball before finding Mulumbu with a neat lay-off but the midfielder’s shot was tame and Robinson gathered comfortably.
David Hoilett was one of the few shining lights for Rovers in the first-half and he curled wide of Foster’s left post after a typically penetrative run.
David Dunn tested Foster with a low shot in the area as Blackburn finished the half stronger, with the Baggies having lost their early rhythm.
Blackburn came out with real intent in the second-half, with Kean moving Hoilett into a more advanced position alongside Yakubu.
And the 21-year-old winger caused the Baggies defence no end of problems.
Only a terrific double save from Foster prevented Blackburn equalising in the 54th minute. Hoilett superbly backheeled the ball to Yakubu, and Foster dived to his left to save the Nigerian’s shot. The rebound fell to Orr but again Foster beat the ball away with his left hand.
Hoilett held off Jonas Olsson and cushioned the ball back to Yakubu who curled his shot just over the bar as Rovers dominated.
Another excellent run from Hoilett saw the young winger play the ball just behind Yakubu to Jason Lowe who fired well over the bar after electing to hit his shot first time.
Kean’s men were made to pay for their profligacy and failure to turn possession into goals as Fortune hit the killer second after 69 minutes.
Brunt dispossessed Yakubu on the right before turning the Nigerian and curling in an inviting cross which Fortune hammered home from close range at the far post.
The match was put beyond Blackburn when Liam Ridgewell rose above Grant Hanley to head in a fine inswinging free-kick from Graham Dorrans.
Blackburn substitute Modeste was somewhat harshly sent-off late on after kicking out at Jones on the touchline.
Rovers remain in the relegation zone on goal difference after their third straight defeat.