Scunthorpe did all the damage in the opening 19 minutes as they raced into a 2-0 lead.
Leading marksman Gary Hooper opened the scoring in the eighth minute against his former club, lashing an angled shot past goalkeeper Peter Gulacsi for his 26th goal of the season.
Twelve minutes later Hooper turned provider as he set up winger Kevan Hurst to force a shot past Gulacsi from a similar distance.
Scunthorpe dominated throughout and Hereford's hopes of clawing their way back into the game disappeared just before the interval when striker Febian Brandy, on loan from Manchester United, saw his goal-bound shot brilliantly turned away at full stretch by keeper Joe Murphy.
From the corner that followed centre-back Dean Beckwith had a goal-bound header blocked away.
But Hereford faded in the second half as Scunthorpe dominated from start to finish.
The home side missed a number of good chances before striker Paul Hayes finally made it 3-0 in the 79th minute with his 16th goal of the season, rounding off a flowing move with a decisive finish.
In the closing stages midfielder Grant McCann and Hayes again both went close to adding to the score as Scunthorpe produced one of their most convincing home performances of the season.
With six home games still to go from their nine matches remaining, manager Nigel Adkins is confident his side can stay in the top six and secure a play-off place as they seek a quick return to the Championship.
But for Hereford boss Graham Turner it's a quick return to League Two which looms large for his side after just one season at this level.