In the photo, Willis kept the top half of her face hidden as she lounged on her bed and showed off her flattering figure.
The "Shouldn't I Be" singer was color-coordinated in complimenting blue hues, featuring a tiny string bikini top and trendy cargo pants.
Prior to the gorgeous post, Willis encouraged fans to come out and support her performance at the Art Basel.
"Who is in MIAMIIIIIIIIIIIIII????" the "Woman At Best" vocalist teased alongside a descriptive flyer for the "Select.Miami" by Basic.Space event in the Miami Design District.
As she waited for her late-night performance to begin, Willis also followed up her recent Harry Styles fangirl era, joking, "I've never been this close to Harry before!!" as she shared a fan's Instagram Story of their 2022 Apple Replay top five artists, which featured the brunette beauty as No. 1, with the "As It Was" singer coming in a close second place.
The Scarlet Letter actress confessed to being a "Styler" at the beginning of November, when she attended his premiere of My Policeman.
"Just a nice casual evening supporting my best friend Harry Styles, here we are pictured on the red carpet together," Willis satirically captioned a poorly photoshopped image of the two standing side by side.
The last few months have been nothing short of exciting for the musician, as Willis recently celebrated the anniversary of her hit song, "Love Without Possession," on Saturday, October 15.
In an Instagram post at the time, the folk singer wrote, "Today on the first birthday of this precious child of my brain and heart, I feel I have two debts of gratitude (among so so many) to acknowledge: To that tender version of me who’s hard work and dedication gifted me the phenomenal life I have now, and to all of you, who have listened, found yourselves in this story and have so generously shared your reflections with me about what this song means to you.”