Duffin, who has represented Australia 117 times across all formats of the game, will be assisted by vice-captains Molly Strano and Lea Tahuhu.
Since joining the Renegades on the eve of WBBL|03 Duffin has amassed more than 500 runs at an average of 25.
She will take over the captaincy from Amy Satterthwaite who announced her pregnancy last month.
“It’s an exciting time to be taking on this leadership role with the rapid improvement this group has shown over the last two seasons,” Duffin said.
“I’ve thoroughly enjoyed working with these players, I’m humbled the club has put its faith in me and I’m looking forward to working closely with Molly and Lea throughout the season.
“I’ve learnt a lot from playing with Amy and she’ll be a great sounding board throughout the season.
“Working closely with our coach Tim and with the talent emerging in this playing group, I’m really excited about what we can achieve.”
Duffin becomes the fourth player appointed Renegades Captain, following Sarah Elliott, Rachel Priest and Satterthwaite.
“Jess is a highly respected leader within our team and across the competition,” Renegades Coach Tim Coyle said.
“She’s calm, tactically strong, a fierce competitor and has a wealth of experience which will equip her well for the role.
“We’ve got some great experience in the playing group and some emerging leaders so we know Jess will get excellent support from Molly and Lea, as well as the rest of her teammates.”
The Renegades begin the WBBL season on October 19 against Adelaide Strikers.