Rudi Garcia's side kept in touch with Juventus at the top of Serie A with a routine win at Stadio Olimpico
The centre-back opened the scoring as early as the 18th minute, as the Giallorossi dominated from start to finish at the Stadio Olimpico.
A Francesco Totti corner found the head of Mattia Destro and his flick-on was headed home by Benatia, who gave goalkeeper Alberto Frizon no chance.
The goal was the cue for a spell of dominance from the home side as they laid siege to the visitors' goal, with Frizon keeping out Destro, Gervinho and Maicon to leave the scoreline at 1-0 at half-time.
But it was only a matter of time before the home side extended their lead and Destro doubled Roma's advantage on 55 minutes with the simplest of goals, after the Catania keeper fumbled a Maicon cross into his path.
With the visitors on the ropes, two goals soon became three, with Benatia heading home his second of the afternoon and his fourth for his new club.
The game was all but over as a contest, but there was still time for Rudi Garcia's charges to round off the scoring with 10 minutes remaining, as Gervinho fired home to extend Roma's unbeaten run in Serie A to 19 games.