Benzema added his second late on as Zinedine Zidane's men moved up from third to go two points clear at the top ahead of Real Sociedad, who face Celta Vigo on Sunday.
After coming off the bench in Tuesday's 2-2 Champions League draw at Borussia Monchengladbach, Hazard was handed his first start of the season among four changes made by Zidane.
Promoted Huesca made a bright start, with on-loan Wolves forward Rafa Mir putting an early shot wide and then having an effort disallowed for offside.
Goalkeeper Andres Fernandez did well to keep out a Sergio Ramos header at the other end, before Huesca went forward again as Javier Ontiveros brought a save out of Thibaut Courtois and Sergio Gomez sent an attempt off-target.
Hazard then fired the hosts ahead with a stunning strike from around 30 yards out in the 40th minute – only his second goal for the club, and first in just over a year.
And five minutes later, Benzema doubled the advantage, chesting down Lucas Vazquez's cross and thumping the ball home.
Victory looked all but secure when Valverde collected the ball from Benzema and struck past Fernandez in the 54th minute, adding to his goal in last weekend's 3-1 El Clasico win at Barcelona.
Ferreiro reduced the deficit with a close-range finish in the 74th minute, before Benzema headed home Real's fourth in the 90th.
His double came a day on from Zidane stressing there was "no problem" between the French striker and team-mate Vinicius Junior – who came on for Hazard on the hour – after video footage emerged appearing to show Benzema telling Ferland Mendy not to pass to the Brazil international at half-time in Tuesday's game.