More than 10.6 million hectares (26.2 million acres) of land have been affected in total across Australia.
Foreign Secretary Dominic Raab announced a package of UK support, alongside Australian Foreign Minister Marise Payne, during a visit to Australia.
The support also includes the collaboration between the UK and Australian space agencies on preparedness, response and mitigation measures to fight wildfires.
At least 33 people have been killed in the fires across Australia which have destroyed more than 3,000 homes.
Kew Gardens has been working with the Australian Seed Bank Partnership (ASBP) since 2000.
Dr Elinor Breman, senior researcher at Kew’s Millennium Seed Bank, said: “Kew’s scientists will work with the ASBP to conduct emergency seed collecting in areas devastated by the bushfires and longer-term germination research, which will hopefully aid the international effort to restore habitats more quickly in this precious and biodiverse region.”