The "With You" singer shared the below shot of herself on the event's red carpet. She's wearing a low-cut, black patterned dress with gemstones around the waistline.
In the photo's caption, she said it was "one of [her] all time favorite red carpet looks."
She also added the hashtags, "FBF" and "to be 24 again."
Fans are loving the look, as Simpson's photo was received more than 85,000 likes.
See the photo below.