"Secret's out - so here's a free preview of this year's 2016 SI swimsuit issue.
"I was one of the lucky few chosen to be a canvas for a hand painted masterpiece by @joannegair that took 14 hours to put on," Rousey wrote.
"Can't wait to show you guys the final pics when the issue hits the stands."
Gair is the daughter of late National Party Cabinet minister George Gair.
She is regarded as one of the world's leading body painters, becoming a global sensation when she painted Hollywood A-lister Demi Moore for a 1992 cover of Vanity Fair.
Other global stars painted by her include Heidi Klum, Rachel Hunter, Sarah O'Hare and Jessica Gomes.
Describing her body-painting work in an earlier interview with the Herald, Gair said: "You work very close and it's a dance with one another. The body needs to be calm, still and working with the hand.
"It needs to bend in a certain direction."
Gair has also worked on album covers for the likes of David Lee Roth, Tina Turner, Grace Jones, Annie Lennox and Mick Jagger.
The Kiwi also worked on music videos for chart-toppers Madonna, Aerosmith and Nine Inch Nails.
She has worked on other projects with Christina Aguilera, Olivia Wilde, Kate Upton, Lady Gaga and Martin Scorsese.
