Rovers manager Steve Kean celebrated his long-term contract with a third home victory in a row.
Kean this week signed a deal to keep him at the club until the summer of 2013 and, after a hotly-contested 40 minutes, he watched as Gabriel Tamas gave Rovers a huge helping hand with a powerful header into his own net.
The hosts' second came less than two minutes into the second half, David 'Junior' Hoilett sending a blistering shot into the roof of the net, and Blackburn held on reasonably comfortably, although West Brom should have had a penalty for a foul on Peter Odemwingie.
Kean handed starts to January signings Roque Santa Cruz and Jermaine Jones while Albion welcomed back key defender Jonas Olsson after injury and suspension.
Paul Robinson was forced to make a decent save from Odemwingie's fierce shot with only 30 seconds gone, and that set the tone for a lively first half.
In the 13th minute, the Rovers goalkeeper was almost caught out when Paul Scharner nipped in front of him to collect a deflected cross and laid the ball back to Jerome Thomas, whose shot nicked off Robinson and drifted a yard wide of the far post.
Approaching the half-hour mark it was the hosts who were building momentum as Boaz Myhill, who was again preferred to Baggies captain Scott Carson, produced two smart stops in quick succession from Martin Olsson and Christopher Samba.
The big defender then fired another 20-yard effort inches wide of the post but West Brom continued to look dangerous and Thomas drove into the box before seeing his shot deflect off Samba and drop just off-target.
In the 41st minute, though, the Baggies undid all their hard work as Tamas inexplicably headed David Dunn's cross into the top corner under only slight pressure from Santa Cruz.
Rovers could even have been two up at half-time had Myhill not thrown a hand out to push behind a stinging shot from the Paraguayan, who was coming more into the game after a quiet start.
Blackburn deserved their lead, even if the goal was somewhat fortunate, but there was nothing lucky about their second, which came only 78 seconds into the second half.
A neat touch on his chest from Nikola Kalinic set Hoilett on his way and the 20-year-old jinked past Tamas before unleashing a shot from 20 yards that flew over Myhill and into the net.
It was the Canadian's first Premier League goal and it may be some time before he scores a better one.
At the other end, the impressive Thomas continued to threaten the Rovers defence and he curled in a 25-yard effort that would have nestled in the far corner had Robinson not got fingertips to it.
Blackburn right-back Michel Salgado then went after his first league goal, striking a volley that was punched away by Myhill, while Thomas and Robinson continued their battle, again the goalkeeper coming out on top.
Having made a good impression on his debut, Jones should have blotted his copybook by conceding a penalty in the 68th minute for an inadvisable lunge on Odemwingie, only for referee Mark Clattenburg to inexplicably award a free-kick instead.
The offence was clearly a yard inside the area but the Baggies' protests were in vain and Chris Brunt slammed his kick into the wall.
West Brom continued to press but they were reduced to long-range efforts as Rovers comfortably kept the visitors at bay, and indeed it was Kean's side who came closest to adding to their lead.
With the clock ticking into three minutes of injury time, Olsson drove into the box and tested Myhill with a stinging shot, with substitute Jason Roberts just failing to convert the rebound.
And the day almost ended in perfect fashion when Santa Cruz, looking suspiciously offside, curled a shot just over the crossbar with Myhill rooted to the spot.