The 31-year-old reality star was promoting her new fragrance True Refection at The London Hotel in West Hollywood when an unidentified woman pelted her with white powder.
Dressed in a black blazer, leather trousers and an electric blue blouse, Kim's hair and entire back were covered by what firefighters later found to be cooking powder.
According to TMZ.com, security guards took her to a private room where she brushed herself down before choosing to return to the event.
Talking to E! News, the shocked star said: "That probably is the craziest, unexpected, weird thing that ever happened to me.
"Like I said to my makeup artist, I wanted more powder and that's a whole lot of translucent powder right there."
But little sister Khloe, 27, does not find the incident quite so funny. She tweeted: "I wish I was with my sister tonight. I bet you that woman wouldn't have dared tried a thing ..."
According to the US website, the woman tried to flee but was held by Kim's press officer.
Los Angeles police have confirmed Kim declined to press charges but a non-criminal battery report was still filed before the woman was released.
Kim's best friend Jonathan Cheban almost fell victim to a similar fate when someone tried to flour him in the face as he walked with Kim in New York last December.
Referring to Kim's estranged husband Kris Humphries - who she filed for divorce from after just 72 days of marriage in October - the person is said to have shouted: "This is for Kris Humphries!"
Kris subsequently denied any involvement and Jonathan told US Weekly: "I think it's pathetic that someone would go to this length to show their support for someone. With fans like that, who needs enemies?"
- BANG! Showbiz