Goals from Teddy Sheringham and Hayden Mullins lifted West Ham out of the Premiership relegation zone to ease the pressure on boss Alan Pardew.
Sheringham opened the scoring for West Ham
Sheringham rose superbly to guide home a header after Yossi Benayoun crossed on 21 minutes - the first time he had scored since turning 40 in April.
With 10 minutes left, Mullins got a foot to Matthew Etherington's corner to thump the ball past Brad Friedel.
Late on David Bentley struck to capitalise on a Robert Green error.
West Ham turned in a mixed performance - vibrant in patches but riddled with nerves, which was perhaps understandable given their precarious league position after a horrendous run that has led to them losing eight successive games.
Mark Hughes' side found it hard to get behind the West Ham defence and it was not until the 73rd minute that Green had to make his first serious save when he spooned away the ball after Lucas Neill's instinctive shot.
The visitors might point to the loss of Jason Roberts, who was carried off to be replaced by Francis Jeffers on the half-hour, as a mitigating factor in their defeat.
However, having drawn at Liverpool a fortnight ago, Blackburn have now lost two league games in a row.
It took a good 15 minutes for West Ham to find any rhythm and when they did, Pardew's side began to trouble Blackburn on the wings.
Freed by Sheringham's clever flick, Matthew Etherington over-hit his cross, with Blackburn's defence in retreat.
A second cross - this time from the other flank delivered by Bobby Zamora - drew a one-handed save from Brad Friedel but there was no West Ham player following up.
A third cross resulted in West Ham's opener as Sheringham rolled back the years with an angled header.
Benayoun teed up the cross like a golfer chipping from a bunker and Sheringham rose to power a header into Friedel's top left-hand corner.
It was West Ham's first goal in over eight hours of football and the first time Sheringham had scored since March.
When he was substituted in the 77th minute, Sheringham received a huge ovation from the Upton Park crowd.
The second half drew a more spirited performance from Blackburn and, with more fortune Neill, might have equalised but his shot went straight to Green.
West Ham immediately broke and Friedel did well to stop Bobby Zamora scoring.
But West Ham did not have to wait long for their second goal, Mullins throwing himself at the ball as Etherington swung in a dangerous corner.
Blackburn pulled a goal back in the second minute of stoppage time when Bentley reacted quickly to punish Green for his failure to hold Benni McCarthy's low shot.
Bentley's goal ensured it was a tense final two minutes and Francis Jeffers almost snatched an equaliser with a looping header.
West Ham: Green, Spector, Ferdinand, Gabbidon, McCartney (Dailly 89), Benayoun (Bowyer 81), Mullins, Reo-Coker, Etherington, Sheringham (Harewood 77), Zamora.
Subs Not Used: Carroll, Mascherano.
Goals: Sheringham 21, Mullins 80.
Blackburn: Friedel, Neill, Khizanishvili, Ooijer, Gray (McEveley 81), Bentley, Mokoena (Gallagher 72), Kerimoglu, Peter, McCarthy, Roberts (Jeffers 28).
Subs Not Used: Brown, Henchoz.
Goals: Bentley 90.
Ref: A Wiley (Staffordshire).