Kim, 35, had more than £8.5 million worth of jewellery stolen after five masked gunmen held her at gunpoint, locked her in the bathroom and tied her up in the early hours of October 3.
Kourtney, 37, appeared on Australia's Today Extra and said that Kim "is still not doing great" after the "traumatic" ordeal.
Kourtney revealed: "You know, she's not doing great. I think we're all really still shaken up.
"I think she has a big supportive family and I know that, like, all of the traumatic things that we've been through, you know, we get through them together as a family and that's what family is about."
Kourtney's comments come after the security guard who was on duty - known only as Abdulrahman, 39 - recalled the shocking moment thieves broke into the lavish Hôtel de Pourtalès, with the father-of-one confessing that he let them in because he thought they were police officers.
He said: "I went up to the apartment with the robbers. I was tied up in the first minutes, with handcuffs. I was in the room of Kim Kardashian. One was attacking her, the second one was with me. I saw Kim being pulled out of bed.
"I told him, I ask you, don’t hurt her. I repeated it. He told me, don’t worry, we are here for money. I repeated another time, please don’t hurt her. He told me: Keep calm and all will be OK. Don’t move or make a sound," he went on.
Abdulrahman then said that Kim asked him if "she was going to die", with her immediately worrying about her family and children.
He continued: "One of the gang kept telling her to shut up. I put my hand on her shoulder and told her to be calm. I said, you have to be silent, you know. She sat down on the bed. She asked me, are we going to die? I said, I don’t know, how can I know?'
"She said, I have family and babies. I told her, me too, I have one son. And she began to scream again. That’s why he put the tape on her mouth. A long piece of tape, all the way round her head," the guard added to the Mail Online.
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