Taking to Instagram, the Keep Up With The Kardashians star posted a stunning black-and-white picture of the parents-to-be cradling her very obvious baby bump.
A delighted Khloe captioned the snap with an emotion-filled message.
"My greatest dream realised! We are having a baby!" the 33-year-old wrote.
"I had been waiting and wondering but God had a plan all along. He knew what He was doing. I simply had to trust in Him and be patient."
"I still at times can't believe that our love created life! Tristan, thank you for loving me the way that you do! Thank you for treating me like a Queen! Thank you for making me feel beautiful at all stages! Tristan, most of all, Thank you for making me a MUMMY!!! You have made this experience even more magical than I could have envisioned! I will never forget how wonderful you've been to me during this time! Thank you for making me so happy my love!"
"Thank you to everyone for the love and positive vibes! I know we've been keeping this quite but we wanted to enjoy this between our family and close friends as long as we could privately. To enjoy our first precious moments just us ❤️. Thank you all for understanding. I am so thankful, excited, nervous, eager, overjoyed and scared all in one! But it's the best bundle of feelings I've ever felt in my life!"
Since posting her happy news in an Instagram snap, the much-loved reality star tweeted: "I was so nervous to post our announcement but WOWWW I am overwhelmed with the response by you guys!!! Thank you! Thank you! ❤️❤️❤️❤️ I love you guys!!"
Kloe reportedly met her NB star boyfriend Tristan, 26, in September 2016. Tristan is already a father to Prince, 9 months, with ex-girlfriend Jordan Craig. Khloe was previously married to Lamar Odom, who has had a very public battle with drug abuse.
WATCH Kris Jenner pretty much spilled the beans on Khloe's pregnancy before her announcement. Article continues after video...
It has been no secret that Khloe had deep desires to one day become a mum. Speaking to ES magazine earlier this year she said: "I would love to have a family. We've talked about it. He [already] is a father and I know for a fact that he would be an impeccable father."
"I definitely want to be a mum, but I don't put the pressure on it. It's not like, 'The clock is ticking.' I feel in my soul it will happen."
Until now, the whole Kardashian family have avoided questions about Khloe's pregnancy like the plague - Kim recently went so far as drinking actual fish juice rather than respond to the rumours.
It will be a busy time for new bubs in the Kardashain family. Last month, Khloe's older sister Kim confirmed that she and Kanye are expecting their third child — another girl — via surrogate. Meanwhile, rumours have been circulating for months that the youngest of the Kardashian clan, 20-year-old Kylie Jenner, is also expecting her first child. Although the family are yet to comment on her reported pregnancy.