Following a disappointing first-half display in which Andy Todd had given Rovers the lead, the hot-shot Hammers hit back with goals from Teddy Sheringham, Nigel Reo-Coker and Matthew Etherington to give them heart for the tough times that, undoubtedly, lie ahead in the months to come.
Already tagged as the bookmakers' favourites for relegation, following their two-year Premiership famine, the Hammers kicked-off hungry to overturn the odds.
Marlon Harewood had the perfect chance to set them on their way as early as the fourth minute when he raced clear only to drag his low angled shot across the face of the exposed Brad Friedel and the far post.
But looking light in attack, hurried in midfield and hesitant in defence it was soon apparent that they could not afford any loss of concentration against a Blackburn side eager to expose any chinks in the East End armour.
Indeed, Robbie Savage soon saw his goal-bound, 20-yard free-kick cleared off the line by Paul Konchesky and while West Ham managed to clear that one, they were not so fortunate on 17 minutes when they failed to deal with Morten Gamst Pedersen's corner and Todd pounced to sweep home a low eight-yarder.
Sheringham also had a low 18-yard shot saved before he scooped over from similar range and just before the break Friedel recovered to block the veteran's sliding effort as they both grappled for a loose ball.
Fortune might have deserted him before the break, but just 45 seconds into the second half, luck was on the 39-year-old striker's side when Yossi Benayoun's threaded pass broke to him off Todd and he levelled with a clinical, low six-yard shot.
And with the East End decibel levels still rising, Sheringham might have bagged a second just minutes later when he toe-poked Etherington's low shot inches wide.
On the hour, Todd was denied a second, too, when Konchesky made his second crucial goal-line clearance of the game but, from almost restoring their lead, Mark Hughes' side quickly found themselves trailing.
Etherington charged at the Rovers defence and then slipped the ball to Reo-Coker who side-stepped Aaron Mokoena and let fly with a rising 18-yarder that scorched under Friedel's left-hand angle.
Following their shaky first half, West Ham were now looking like they had never been away from the Premiership and, with ten minutes left, Benayoun strolled on to Brett Emerton's careless stray pass into no-man's land and cleverly crossed to the far post where Etherington comfortably slotted home their third goal.
Rovers' frustration at having lost their stranglehold on the game was underlined by substitute Paul Dickov who - having been on the pitch for just ten minutes - was then shown a straight red card for a reckless two-footed lunge on Konchesky.
MAN OF THE MATCH: Danny Gabbidon (West Ham) - The former Cardiff man produced an assured display on his Hammers debut as he helped to cancel out Rovers' increasingly shot-shy attack.