During a recent episode of Keeping Up With The Kardashians, Khloe, 30, was seen begging 28-year-old Rob to accept help.
The supportive sister allegedly considered calling the police this weekend when her brother disappeared without an explanation.
A Kardashian insider told RadarOnline: "Rob had been at Khloe's house Friday morning, and left without telling anyone where he was going.
"Khloe was out of town but her assistant was at the house. After learning Rob had left, Khloe began calling and texting her brother to check-in. After not hearing from Rob for over 24 hours, she called her mom, Kris [Jenner]."
According to the source, Khloe wanted to call the police but Kris, 59, wouldn't let her.
They continued: "Kris began calling Rob's friends, and dispatched staffers to go by Rob's condo.
"Rob wasn't at his condo, and his friends had no idea where he was. [Kris] thought Rob would get very angry that the cops were called, and it would have created a media circus.
"Finally on Monday morning, Rob came back to Khloe's house not offering any explanations for his whereabouts."
Khloe recently opened up about her brother's social anxiety, and it is believed he is suffering heavily from depression.