The adorable snap features Kourtney and partner Scott Disick's youngest child Penelope crawling over her mother as they lie on a sun lounger.
Wearing a glamorous gold bikini, Kourtney looked content as she relaxed with her little one. She captioned the shot with a simple smiley face that had hearts in its eyes.
Kourtney has been seen around the exclusive resort the Hamptons lately, as she films her new reality show.
Kourtney & Khloé Take The Hamptons will see Kourtney and her younger sister opening a new Dash store in the Hamptons, and Kourtney has been making the most of the location, which is near to New York City.
She has also shared snaps on her Instagram account which show her taking to the skies in a helicopter for a tour over the Big Apple, and her rainy Fourth of July celebrations.
The Keeping Up With the Kardashians star and Scott are expecting their third child in December.
The couple have been together for seven years and are already parents to Mason, four, and Penelope, 23 months.
It was first reported at the beginning of June that the TV star was expecting, with a source telling US Weekly: "Kourtney wants to have a handful of kids." Kourtney confirmed the pregnancy during the premiere episode of the reality show's new season.
The 35-year-old was seen breaking the news to her long-term partner Scott at the end of the episode, in a montage of clips showing viewers what to expect during the forthcoming new season. "I'm pregnant," she says. "It was not a plan."