Rob Kardashian Smiles with His Sisters at Khloé's 'Family Only' 36th Birthday Party

Rob Kardashian was all smiles at his sister Khloé's birthday over the weekend.

On Saturday, the Kardashian-Jenner family gathered in honor of Khloé's 36th birthday, throwing her a very-pink party complete with inflatables, sweets and colorful decorations.

While sisters Kourtney and Kendall Jenner got in a playful tussle with Khloé (caught on-camera by Kylie Jenner), their brother brought nothing but smiles to the occasion.

"Sweet 16 😁 woo," Rob, 33, wrote on Instagram on Sunday, sharing a sweet photo of himself with an arm around Kourtney, 41, as he wore a blue hat and a black hoodie. Mom Kris posted the same photo on her own account, captioning it, "These two cuties 😍."

The matriarch also documented the festivities by capturing a joyful snapshot of her adult children clowning around together, with Kourtney and Kim not pictured.

"4 out of 6 #happybirthdaykhloe," she captioned the shot, which showed Rob laughing with Khloé in front of a pink-themed dessert table, as Kendall, 24, danced nearby and Kylie, 22, snacked on a treat.

From left: Rob Kardashian, Khloé Kardashian, Kendall Jenner, Kylie Jenner

On Twitter, Khloé thanked everyone for sending positive birthday wishes and explained that the celebration was limited to just family amid the ongoing coronavirus (COVID-19) pandemic.

"I had the most magnificent birthday!!! It was family only. We just aren’t comfortable being around too many people but the decor was OUT OF THIS WORLD!!!!!" wrote Khloé on Sunday night. "I wanted to thank you ALL for sending me so many beautiful and kind wishes. I love you very much."

RELATED: Khloé Kardashian Celebrates 36th Birthday with Family — and Gets into Playful Fight with Sisters

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Rob also shined at another one of his big sisters' birthdays this year. Back in April, as Kourtney turned 41, she revealed that her brother gifted her with a timeless present.

The Poosh creator revealed at the time that Rob got her something that couldn’t be bought in a store: her late father Robert Kardashian Sr.’s record collection.

Kourtney snapped a picture of the nostalgic and sentimental gift on her Instagram Story, writing that it was her “favorite birthday present” this year.

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Over the weekend, Kris shared an emotional birthday tribute to her "special bunny" Khloé on Instagram, writing that she hopes her daughter has "so much sparkle in your day today my beautiful girl."

"You are an amazing daughter, sister, auntie friend and confidant and you are the entire world to your precious daughter True!!!!!! What a spectacular Mommy you are!!!" she said. "I am beyond proud of you for all you are and how you are the most loving caring and generous soul with a smile that lights up every room you walk into... you always lift all of us up and are everyone’s greatest cheerleader."

Kris added, "Thank you for being such a light in my life and such a huge part of my heart... I love you my bunny what a blessing you are!!!! Oh and did I mention you are gorgeous inside and out???? I love you.. Mommy."