The star shared a video on the social media platform, wearing a tight pink dress and necklace with a heart pendant.
She is seen standing in front of 'Happy Birthday Khloe' balloons before she picks up and hugs her daughter True Thompson.
The Keeping Up With The Kardashians star caused alarm among fans, with many commenting on how different she looked after her recent weight loss and plastic surgeries.
"You don't even look like the same person anymore," one said.
"Her face looks completely different," another said.
"Who is this because it's definitely not Khloe," a third added.
On an Instagram post thanking people for the birthday wishes, fans suggested the star had dropped too much weight.
"Please don't get any thinner," one wrote.
"She's so skinny," another concerned fan said.
"You need to slow down a bit," a third added.
Other fans praised Khloe for how beautiful she looked, hitting out at those criticising her body.
In June Khloe broke her silence on her recent weight loss during an interview with the YouTube talk show Hot Ones.
She began working on her 'revenge body' after her split from basketballer Tristan Thompson, telling the Hot Ones host she had been working on chiselling her body.
"I like muscles," she said. "I don't like to be just thin. It is really empowering.
"I feel a sense of accomplishment after my workouts. Knowing I'm working on parts of my body."
Last month Khloe stunned her followers when she showed off her 'insane' abs in an orange bikini.
Her followers loved the look, with one user commenting, "Are you for real!!!!! That bod."
"Body goals," another added, while a third wrote, "Your swimwear looks so insane."
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