The reality TV star's boyfriend Kanye West shared the couple's happy news during a performance at Revel in Atlantic City, New Jersey on Sunday, and the brunette beauty's representative has now confirmed the news.
During the show, Kanye - who has been dating Kim since April 2011 - told the audience to "stop the music and make noise for my baby mama."
While Kim - who is believed to be around 12 weeks pregnant - hasn't spoken about her pregnancy, her family are delighted by the news.
Sister Kourtney Kardashian - who has two children, three-year-old Mason and five-month-old Penelope, with partner Scott Disick - tweeted: "Been wanting to shout from the rooftops with joy and now I can! Another angel to welcome to our family. Overwhelmed with excitement! (sic)"
Sibling Khloe Kardashian added: "Keeping secrets is hard with so many family members! Especially when you are so freaking excited!!!!! LOVE is everything!!!! (sic)".
And Kim's mother and manager Kris Jenner is delighted.
She tweeted: "Im a happy girl !!!!!!!!! Wowza! (sic)"
Kim, 32, and 35-year-old Kanye spent the festive period together and were seen with the 'Keeping Up with the Kardashians' star's family watching her brother-in-law Lamar Odom playing basketball for the Los Angeles Clippers on Christmas Day.
However, they left at half time with Kim later tweeting she felt "unwell".
She added: "In bed with the flu all day. Praying this goes away fast!"