The in-form striker, who has now scored twice in his last three outings, opened the scoring with a relatively simple sidefooter on 24 minutes before doubling his side's lead early in the second half with a fine, far more noteworthy, individual effort.
The result means that Madrid's hopes of ending the weekend just four points behind Barca are still intact, with the current league leaders facing a tough fixture at Sevilla on Sunday.
Madrid were deprived of Cristiano Ronaldo's services as the Portuguese was given another weekend to recover from a muscle strain while Pepe and Xabi Alonso were rested with one eye on Wednesday's Champions League clash with Lyon.
Yet Jose Mourinho was still able to field a potent line-up, with Emmanuel Adebayor, Angel di Maria and Mesut Ozil supporting Benzema up front.
And it was the latter two who combined to open the scoring midway through the first half, Ozil unlocking the Hercules defence with a fine pass to Alvaro Arbeloa who centred for Benzema to sidefoot home with ease.
Three minutes later Adebayor could have doubled their lead with a towering header that Juan Calatayud did well to tip over the bar but despite having conceded, Hercules responded well and could have found an equaliser soon after.
Real were soon back on top though and after the break they made their intentions clear as Adebayor hit the bar with a tremendous effort that the Togo hitman swept first-time onto the woodwork.
Benzema went close to adding a second with a fine piece of skill to dink the ball over his marker and fire on goal before he did manage to double his side's and his own personal tally.
There was an element of fortune as Abraham Paz misjudged the flight of the ball to allow him to run in on goal but there was nothing lucky about his finish. The France international cut back inside as he approached the byline before firing a low curling effort into the far corner.
Two-nil up and considering Hercules have scored just once away from home this season - on the night they passed the 1,000 minute mark without a goal on their travels - there appeared little chance of the visitors getting back into the game.
And so it proved as Madrid closed out the remainder of the match on the front foot.
Ozil saw a free-kick tipped over the bar and substitute Sami Khedira failed to find the back of the net after Adebayor fluffed his lines in front of goal but in the end two goals was enough for Mourinho to register a 150th consecutive undefeated home match - and put the pressure firmly back on Barcelona.
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