Kim's low key celebration included a catered family dinner from the Armenian restaurant Carousel, a churro stand and a beignet truck.
In the rare footage, Kim filmed daughters North and Chicago, as well as niece Penelope following two men in their house.
One of the men looked like a skinnier Rob, 32, who was seen wearing black shorts and a black tee. While his face is not shown, his arms appeared to be full of tattoos like the sock designer's own.
“I love my family," the mother of four wrote below the video. In sister Khloe Kardashian's Instagram Stories from the party, a woman who sounded like Kylie Jenner can be heard calling out her brother's name, "Robert! Robert!"
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Kylie, 22, did a special rendition of her hilarious "Rise and Shine" meme for Rob on October 19. The Author George founder shared an Instagram video of his younger sister quietly singing. "Rise and shine ?," he simply captioned it.
Rob's weight has fluctuated over the years, but he revealed this past June that he was back at the gym. He posted a Twitter pic from his workout and wrote, “Day 1 all good."
A source told People in 2018 that the E! personality “can’t seem to get healthy even though he says he wants to be." His biggest struggle is trying to maintain a healthy diet. “Food is the hardest part for him. He’s a big comfort eater," the insider added at the time.
What are your thoughts on Rob's new slimmer look? Sound off in the comments below!