At the end of July, ASX 200 boards had 31.3% female directors, according to the Australian Institute of Company Directors (AICD).
The figure is up from 20.6% five years ago and 30.7% at the end of April.
"In just five years we have seen boards successfully reach 30%, by voluntarily committing to the target," AICD CEO and managing director Angus Armour said.
"We are very pleased to see that the momentum continues as organisations make diversity a priority. We have seen the larger listed companies doing the heavy lifting for some time now, so it is particularly encouraging to see that the ASX 300 is also nearing the 30%."
Fortescue Metals Group continues to be a standout, with four female directors, including CEO Elizabeth Gaines, while South32 has three female directors, including chair Karen Wood.
Later this year, Lynas Corporation will be the first ASX miner to have a female CEO, Amanda Lacaze, and female chair, Kathleen Conlon, following the resignation of Mike Harding on September 30.
Iluka spin-off, Deterra Royalties, which will be a contender for the ASX 200, has majority of women directors, including chair Jenny Seabrook.
Rio Tinto appointed three female directors earlier this year to take the proportion of women on its board to 25%.
"However, it is important to recognise that diversity goes beyond a ‘one and done' mentality," Armour said.
"There are still 29 companies in the ASX 200 with only one female director. Ultimately, all boards should be working towards a 40:40:20 model for diversity in their leadership."
At April 30, there were four ASX 200 companies with no female directors: TPG Telecom, Pro Medicus, Silver Lake Resources and New Hope Corporation.
Three have since rectified that, leaving Silver Lake as the only ASX 200 company without a woman on its board.
"The invitation to join us in the current century is very much open," website Women's Agenda said in response.
Nicola Wakefield Evans, chair of 30% Club Australia, applauded the companies that had rectified the underrepresentation of women on their boards.
"Now is not the time to become complacent. Companies at the top of the ASX continue to lead the charge, with more than half of the ASX 100 now at more than 30% women on their boards, and 28 boards comprised of more than 40% women," she said.
"At the same time, more than half the companies in the ASX 201-300 category have only one woman or none at all.
"There is no shortage of qualified, board-ready women in Australia. We look forward to working with stakeholders on our goal of achieving gender parity on boards and addressing systemic barriers to this change."
Bellevue Gold is a standout in the ASX 300, having appointed Shannon Coates and Fiona Robertson as directors in May.