In one pic, Sarah, 47, put her cleavage on display as she highlighted her figure in a plunging black lace bustier.
She paired the top with high-waisted blue jeans, sparkly diamond necklaces, a full face of makeup, and her blond hair flowing straight down.
A second snap captured the Cruel Intentions star showing off her full look as she posed for the camera.
“Vegas Era Sarah is a good time,” Sarah captioned her post.
Sarah also shared a pic on her Stories of her rocking the same outfit with the sunlight beaming on her face.
“Still catching that Vegas light,” she wrote above the photo.
Fans praised the Buffy the Vampire Slayer for her appearance in the comments, with one writing, “Super cool and Always beautiful.”
Another remarked, “Aged like fine wine! You still have a Buffy body!”
A third echoed, “Always looking absolutely Gorgeous.”
“How does she not age? She must really be the slayer,” said a fourth, mentioning her role in Buffy.