Supremo makes it abundantly clear that the Italian international midfielder will not be sold as "new era" begins, with the 27-year-old set to be offered a contract renewal
The new chief, who took over from the Sensi family, was unveiled at the club's Trigoria training ground in Rome, and on the agenda first was De Rossi's future.
"We admire De Rossi's ability, and we firmly want him to stay at Roma," DiBenedetto said.
The 27-year-old has been linked with a move to Inter and Chelsea recently as his contract expires next year, but his current side have not offered him a new deal.
"De Rossi comes from Rome and we want him to stay. We want him here and we will work hard to sign him to a new deal," DiBenedetto added.
The American tycoon went on to say that he expects changes following years of the Sensi family's leadership.
"A new era is about to start that will change the way we play football. We want to realise a dream and that will take time," he said.
"I want to thank the Sensi family who were here before me and I want to thank the team which I have only just met.
"We will all work hard to develop a new culture of sport and build a team with players who will give the maximum."
Roma are currently at Trigoria preparing for pre-season. On Wednesday, director of sport Walter Sabatini said there was no chance of De Rossi leaving.