The Serie A leaders got their UEFA Champions League campaign off to a perfect start by beating last season's finalists in an eventful Group F encounter at the Stadio San Paolo.
Gonzalo Higuain's first-half header and a sublime free-kick from Lorenzo Insigne after the break gave Napoli a 2-0 lead, before Juan Camilo Zuniga's late own goal gave Dortmund - who had goalkeeper Roman Weidenfeller sent off on the stroke of half-time - a glimmer of hope.
And while Benitez was slightly disappointed with the fact his team came under late pressure despite the visitors' numerical disadvantage, he was pleased Napoli managed to see the game through and claim a vital three points.
"We lacked a bit of control on the game in the final minutes. We needed more possession, but unfortunately the third goal didn't come and we suffered until the end," said the Spaniard.
The former Liverpool, Inter and Chelsea manager went on to praise the Napoli faithful for their vociferous support throughout the match, adding that his charges should gain belief from defeating one of the favourites to win the competition.
"The atmosphere here is fantastic and our fans are wonderful," he stated.
"This victory is good for our self-confidence, let's see how far we can go."
