Ferrer, ranked five in the world and with five titles to his name this season alone, was rarely in contention against the seventh seed.
Benneteau held his nerve to win through in 98 minutes, setting up a final against Juan Monaco in the process.
"It was difficult to beat him, because David is a very solid player," said Benneteau. "I knew I had an opportunity, as I had beaten him in the past. I am happy I did it. My chances are 50-50 for the final. Monaco is a very consistent player."
"I was okay today, in good condition, but Julien played a very good match; better than me," admitted Ferrer.
Monaco for his part faced a sterner task against Kei Nishikori in the other semi-final, having to save a match point before emerging a 6-2 2-6 7-6(4) winner.
The pair scrapped for two hours and 43 minutes, with the Argentine coming through at the crunch moments to shade a third set with precious little separating the pair.
"Nishikori played very well," said Monaco. "He came back in the second set, playing better than me. The final set was up and down, he had one match point, then I fought back and I am very happy the way I finished the match. I think the crowd enjoyed it."