Two goals apiece from Dimitri Payet and Emmanuel Emenike and one for Victor Moses overwhelmed Blackburn who had jolted their Premier League opponents into life by taking a 20th-minute lead.
Both sides ended with 10 men with Blackburn losing Chris Taylor after 55 minutes for a second yellow card after a trip on Moses and the Hammers having to do without Cheikhou Kouyate for the closing stages after he was shown a straight red for tripping Adam Henley.
In-form Tottenham's hopes of winning the FA Cup for the first time since 1991 were dashed by London rivals Palace with Martin Kelly's goal on the stroke of halftime proving decisive.
West Ham march on though and their display against Rovers sent the 7,000 visiting fans at Ewood Park home believing some long-awaited silverware is on the horizon.
Their 1980 FA Cup triumph was their last trophy.
"After the first 20 minutes we played fantastic," West Ham boss Slaven Bilic told BT Sport.
"We played great football. It looked easy but it's not easy. Blackburn are a big club and in the Championship, but we made it look easy because our performance was spot on."
In a sparsely-populated stadium, the hosts went in front when Ben Marshall's pinpoint shot crept inside keeper Darren Randolph's left-hand post.
West Ham quickly levelled though when Moses's speculative shot evaded Rovers keeper Jason Steele.
If Steele could have done better with that effort, he stood no chance with Payet's curling free kick after 36 minutes.
The second half was one-way traffic with Nigerian Emenike producing two astute finishes and being denied a hat-trick by the post after some nifty footwork.
Frenchman Payet completed the rout with a fine solo effort.
Later on Sunday Chelsea host Manchester City.
(Reporting by Martyn Herman, editing by Pritha Sarkar)
Share
