The adorable snap, which was posted on Kim Kardashian's Instagram account, shows one-year-old Penelope hugging her younger cousin Nori.
"BFFS," wrote Kim, referring to the youngsters' close relationship.
The picture quickly garnered 1.26 million likes from Kim's Instagram followers and more than 1,000 retweets on Twitter.
The image shows seven-month-year-old North wearing a white babygro and a yellow bib, while Penelope, whose parents are Kourtney Kardashian and Scott Disick, is dressed in a warm grey jumper and leggings.
Kim's Instagram post comes just days after she revealed some of her wedding plans on Jimmy Kimmel Live.
The 33-year-old confirmed that she and Kanye West are planning to marry in Paris, which Kim says is the couple's "second home".
"We'll be getting married this summer, hopefully in Paris," Kim told Jimmy, adding that Kanye will "take care of the music and I'll take care of the seating chart."
Reality TV star Kim said that rapper Kanye was taking a keen interest in planning the big day.
"I know they think, or they say that the guy usually doesn't care and just shows up," she said. "Kanye really cares, he's really passionate about it so it makes my job so much easier."
"But I love it because he knows what he wants and I love him for that."