"❤️Blast from the past......... #BeforeGravitySetIn 😜 #WorkingGirl #CancunMexico1990 with my favs @mpkaynephoto," the 51-year-old captioned the sexy shot.
In the photo, the Dutch beauty poses for the camera wearing a revealing neon green swimsuit while exposing her tanned backside.
Foster first found fame as a model, before landing a starring spot on Bravo's "Housewives" franchise in 2012.
Yolanda's daughters with ex-husband Mohamed Hadid are both following in her footsteps, too. The reality star's 19-year-old daughter Gigi Hadid has been killing it at Fashion Week all around the world -- from New York, to Milan and now Paris!
And now the "Sports Illustrated" star's 18-year-old sister, Bella Hadid, has been making a splash in the modeling world, too!
Clearly, good genes run in Yolanda's family! What do you think about Foster's throwback modeling shot? Tell toofab in the comment section below and check out the gallery above to see Gigi's best TwitPics!