A former Mayo minor footballer, the 6ft 2in, 95kg full-back has been ever-present in the Connacht squad since his return to the province in 2007 following a four-year stint with Harlequins.
Having played for Ireland at Schools, Under-21, Sevens and 'A' level, the Ballina native is one of a select few to earn 100 caps for Connacht.
He was part of Connacht's 2010 Amlin Challenge Cup semi-final team that narrowly lost to Toulon at the Sportsground.
Speaking about the captaincy role, the 29-year-old said: "I'm delighted to be asked to captain the team for the year. Playing for your province is a huge honour and to be asked to captain the side only adds to that.
"It is a very exciting time for Connacht at the moment, the launch of the new league, the Heineken Cup and the new developments at the Sportsground. Being part of that team is very special.
"There's been huge support for Connacht in the last couple of years and this season. With the number of season tickets already sold, there should be a great buzz at the Sportsground."
He added: "It's up to us now to put in the performances on the pitch and everyone's looking forward to getting the league started this weekend."
Commenting on Duffy's selection as skipper, Connacht head coach Eric Elwood said: "Gavin is one of our most senior players and a great servant to the province. He has shown huge leadership both on and off the pitch.
"John (Muldoon) has been a terrific captain for the last three years and will continue to lead by example, but now it's Gavin's opportunity to lead the team."