A 26th-minute strike from Edward Upon set up their victory when he drilled a low shot past Bulls goalkeeper David Cornell.
Andy Williams swept home Yeovil's second 13 minutes into the second half with a sparkling 20-yard effort.
Dominic Blizzard made sure of victory by producing a blistering drive in the 72nd minute.
Nathan Elder spurned a host of chances for Hereford in the first half.
The Bulls frontman was withdrawn as part of a double substitution at the interval, but replacements Delroy Facey and Yoann Arquin endured similar frustrations.