Freo, which also occupies sixth position on the current AFL home and away season ladder, moved up two places after an eighth-placed finish last year.
The club’s membership total of 42,762 is a seven per cent increase, or 2,908 members, on last year’s membership level figure.
More than 650,000 fans became a member of their AFL club of choice in season 2011, the highest figure in competition history.
Aided by record membership increases for 10 clubs and the addition of a 17th team, the AFL's final combined membership figure at the June 30 deadline was 650,373 - up from 614,251 last year.
AFL CEO Andrew Demetriou thanked fans for their support.
"On behalf of the AFL, I wish to thank those supporters who continue to make the commitment to join an AFL club," Demetriou said.
"Their passion for our game is the lifeblood of our sport across the country."
Club membership has now risen every year since 2001, with the only drop since 1990 coming in 2000, when the season started early to avoid a clash with the Sydney Olympics.
On top of the record membership figure, Demetriou said the League was also heading towards a record total attendance for the season.
"Membership and match-day attendances are the AFL's most important indicators of the game's health," Demetriou said.
"The clubs and players deserve great credit for the standard of the game on the field and also for the many hours that are invested in connecting with supporters in every part of the community."
Eight clubs, including Fremantle, now boast membership bases of over 40,000.
