Billionaires Andrew and Nicola Forrest will step down as co-chairs of the philanthropic foundation they founded together more than 20 years ago.
Lawyer Allan Myers KC will replace the pair as the Minderoo Foundation's new chair.
The Forrests will remain involved as non-executive directors.
"We couldn't be more proud of what has been achieved over the past 23 years," they said in a joint statement on Thursday.
"Under Allan's stewardship as the independent chair we know Minderoo will continue delivering on its mission to forge a fair future by challenging inequalities and campaigning for meaningful change."
Mr Myers, who has served on the foundation's board since 2014, said he would work to help realise the Forrest's aspirations to make the world a better place.
"The unprecedented generosity, vision and optimism of Andrew and Nicola Forrest is embodied in the Minderoo Foundation," he said.
Dr 'Twiggy' Forrest said the Minderoo Foundation, which was originally founded as The Australian Children's Trust in 2001, would continue to drive positive change.
"I have an unshakeable passion for steering the world away from a potentially catastrophic future, and will continue to steer Minderoo, Tattarang and Fortescue in the one direction - to ensure we leave our planet liveable for future generations," he said.
The mining magnate and founder of Perth-based Fortescue Metals Group said he would focus his energy on global emissions reduction targets and ending the use of fossil fuels by 2040.
"Scientists and businesses worldwide have endorsed the reality that Real Zero 2040 - the cessation of the use of all fossil fuels by 2040 - is the only way that we will avoid a climate emergency," Dr Forrest said.
The Forrests, who were Australia's wealthiest couple, separated in 2023 after more than 30 years of marriage.