The Slovakian midfielder scored twice for Napoli in their opening clash of the new Serie A season, as the Partenopei looked to throw down the gauntlet to champions Juventus following a summer of heavy spending.
And Benitez was full of praise for Hamsik, believing he will relish his new leadership role at the Stadio San Paolo.
"It was easy for me to decide who would be the captain, because Marek Hamsik is a talented player," Benitez said after the match.
"He's a player who can make the difference and giving him such a responsibility could contribute to enhancing his self-esteem for the future.
"It really was an easy choice, he scored two goals tonight, let's see if he repeats the result each game we play."
The former Liverpool manager still expects significant improvement out of his new side as the season develops despite their impressive opening-day performance.
"Napoli definitely aren't at 100 per cent at the moment," Benitez said.
"There's a lot to do from the physical, tactical and technical point of view.
"The team have just changed, they've just taken a new direction, but the self-confidence they proved today is surely the right beginning and the key for the future.
"But we still have a long way to go ahead of us."