The British-based website claims Macpherson, 47, will join fellow Aussie celebrities Nicole Kidman, Hugh Jackman and Ian Thorpe.
The website quoted Macpherson as saying: "Sport is at the heart of the active lifestyles lived by so many Australians and so the chance to host the World Cup can only inspire future generations to stay active and healthy."
Macpherson's international fame is something that will certainly please the FFA as it spends time at the 2010 World Cup in South Africa seeking more support for its bid, and trying to get ahead of the United States in particular, with England the favourite to win 2018.
The news also comes just hours after Federal Sports Minister Kate Ellis told SBS that Brazil was also looking to support Australia ahead of other bidding nations.
"I met with the Brazilian sports minister yesterday and it was a really positive meeting," she told Les Murray on The World Cup Show from Cape Town.
FIFA will announce the hosts for both the 2018 and 2022 World Cups in December.