De Rossi will keep the role for the entire tournament even if scrum-half and former skipper Alessandro Troncon returns from injury during the campaign.
De Rossi's bow as skipper will be against world champions England at the Stadio Flaminio.
Coach John Kirwan said: "We are starting with the aim of winning the tournament and that is the only acceptable mentality even if I am fully aware of the difficulties in every match we play.
"I know we can do well and I believe Andrea De Rossi has the right qualities to be captain for the 6 Nations even if Troncon comes back earlier than expected.
"De Rossi will stay as captain until the last game with Wales in Cardiff."