Antonio, the club's inaugural skipper, has held the role for five years but feels the time is right to pass on the baton and focus more on her own football.

The 29-year-old has missed just two games since Fremantle's AFLW inception in 2017, and the club is expected to hold a vote to determine its next captain.

Antonio's wife Ebony Antonio has been part of the leadership group since December, 2018 and could be among the contenders vying to be named skipper.

Fellow leadership members Kiara Bowers, Gabby O'Sullivan and Hayley Miller are also well positioned to apply for the role.

"It's a tough decision, but one that I can reflect on and be proud of everything that has been achieved over the past five years," Antonio said of her decision to step down as captain.

"I'm just really proud of where we've been able to take the group and I'm excited to focus on my game this coming season with a different role up forward.

"I can now take a bit of a back seat and focus on myself a little bit.

"I've put a lot of time and energy into the wider group and that's been my role and I've absolutely loved it - but it's time to let the next generation step up and take us forward."

Coach Trent Cooper praised Antonio's leadership qualities.

"I think it's fair to say that Kara has been the face and voice of Fremantle's AFLW team over the past five years," Cooper said.

"She has always led with great strength and by example, never asking anything of anyone that she wasn't already doing herself.

"Kara has been the main driver of culture at the club in those five years and has put us in a really good place in that regard.

"For her to come to this decision speaks volumes of her leadership, which we all know will continue even though she won't have a 'C' next to her name."

Australian Associated Press