Big Darren Moore emerged as West Brom's saviour with a crucial late goal which paved the way for Albion's fourth successive win that keeps them firmly on course for promotion.
Moore rarely scores but this was his second against Palace in two years and could prove to be the launch pad back to the Premiership.
Albion struggled to make an impact but sealed the match with two late goals from Moore and Lloyd Dyer, who recorded his first ever league goal.
Moore played down his goal but admitted: "It is vital to keep winning and I am just pleased to have got on the goalsheet.
"Although we are in a very good position for promotion there is still a long way to go and we can only look to the next match.
"Palace are a very good side and for a long time it appeared as if we would have to be content with a point.
"But in the end we were able to produce a very good win with young Lloyd Dyer again showing his promise." Baggies boss, Gary Megson, said: "Palace are a good side and chances were at a premium.
"It was the type of game everyone expected. I changed a few things in the second half to give us some more options and we managed to get two late goals.
"It was a fair result and a terrific three points at this stage of the season. Darren Moore scored a fine goal and it lifted the tension when the ball went into the net." Palace boss, Ian Dowie, said: "We didn't get what we deserved.
"Defensively we were excellent but sadly we switched off in the last ten minutes.
"Albion are a very good side and they deserve to be challenging for promotion." For much of the game Palace, who have now lost their last three away games, were obviously intent on a containing operation against an Albion side now defeated only twice in the last 14 games.
The Londoners were successful in their operation until the final ten minutes as the infuriating Albion struggled to please the home fans with another colourless performance.
Albion's lack of success until late in the game enabled Palace to gain in confidence as they moved forward in a more attacking mood in the second half but Moore and Sean Gregan were both commanding figures.
As a result Andy Johnson, Palace's leading marksman, could make little impact. He had previously scored 15 goals in 15 games but has now gone three matches without getting on the scoresheet.
The early promise of Albion faded and it was a major worry as they struggled to make an impact and the situation deteriorated when their star player, Artim Sakiri was substituted in the second period.
They only redeemed themselves with a sparkling finish when Moore and substitute Dyer popped up to seal Palace's fate.
Palace, too, were unable to create any clear openings. In the first half Wayne Routledge could only test Russell Hoult with a tame effort which was typical of later goal attempts.
In sharp contrast Nico Vaesen was in outstanding form and played a major role in Palace creating such a good impression against the promotion favourites until Albion cashed in on a good late finish.
Vaesen certainly earned the plaudits for Palace. He kept the visitors in the game in the first half but his best save came in the first minute of the second period.
Lee Hughes, who has shown some of his best form in recent weeks, highlighted his danger to the Palace defence when he cut in from the left and hammered a shot towards the top far corner of the net.
On loan Vaesen, who is to be offered a new contract for next season by Birmingham City, finger-tipped the ball away for a corner.
Albion then struggled to gain the upper hand against a Palace side which displayed skill and flair in attack.
The inability to break down the Palace resistance resulted in Albion's boss, Megson, taking off Sakiri in the 56th minute to be replaced by Jason Koumas who had earlier suffered the indignity of failing to start his first game of the season.
It was a strange decision in view of Sakiri being Albion's most prominent player on only his fifth start this season but it was justified with the end result.
But Megson was obviously far from satisfied with the pattern of play and attempted to bring about a change in fortunes when he substituted Rob Hulse with on loan Delroy Facey.
He made a third change sending on Dyer, who has quickly become a favourite with the Baggies fans.
His pace down the left suddenly opened up Palace and they lost their composure.
The breakthrough occurred nine minutes from time when Moore headed home a right-wing corner from Koumas.
Albion settled the issue with a second goal in five minutes when Facey, on loan from Bolton, pulled the ball back into the path of Dyer to coolly glide his shot past Vaesen.
Man of the match – Artim Sakiri: The Macedonian international was the star of the show before his surprise substitution, his deft touches being the highlight of a moribund game until the last ten minutes.