The picture appears to have been taken in the bathroom of the Versace mansion in Miami, where Kardashian and her sisters have been residing for the past few days.
"Quick swim before the Dash party!" the 33-year-old reality star wrote in the caption.
The image shows the new mom's toned body and curvaceous figure and leaves a lot less to the imagination than the barely-there white one-piece suit selfie she posted last year. Kardashian, who has mentioned she often felt fat-shamed by media during her pregnancy, made sure to point out that the bathing suit belonged to her younger and more petite sister Kylie to showcase how tiny her frame is at the moment.
"Yep stole Kylie's bikini...she's not getting it back," she captioned another photo.
Here's a picture of Kylie wearing the bathing suit earlier that day.
Celebrity Couples of 2014 [PHOTOS]