Duffy is supported on the wings by Fetu'u Vainikolo and Tiernan O'Halloran, who were both regulars last season, while there is a first competitive outing for the dynamic centre partnership of newcomer Mata Fifita and Eoin Griffin.
Kieran Marmion will gain his first senior cap for Connacht at scrum half. He started in the pre-season friendly against Harlequins and also played a pivotal role for the Ireland Under-20s at this summer's IRB Junior World Championship, starting four of their five games en route to a highest ever finish of fifth.
Another regular from last season is out-half Miah Nikora who got a good run-out in both of the province's recent pre-season friendlies.
Ronan Loughney, with 105 caps, provides more experience in the front row with George Naoupu, Denis Buckley and Ethienne Reynecke completing the selected pack.
Looking forward to kicking off the new season, Connacht boss Eric Elwood said: "All the pre-season training has led to this point and we can't wait to get going."
CONNACHT (v Cardiff Blues): Gavin Duffy (capt); Tiernan O'Halloran, Eoin Griffin, Mata Fifita, Fetu'u Vainikolo; Miah Nikora, Kieran Marmion; Denis Buckley, Ethienne Reynecke, Ronan Loughney, Michael Swift, Mike McCarthy, John Muldoon, Johnny O'Connor, George Naoupu.
Replacements: Adrian Flavin, Rodney Ah You, Finlay Bealham, David Gannon, Willie Faloon, David Moore, Matthew Jarvis, Robbie Henshaw.