The former model revealed the news on Twitter, posting, "You've all supported me through bad times so I wanted to share some good news with you. I'm thrilled to say I'm expecting my first child! :)".
Katie, who suffered burns to her face and chest in a violent acid attack arranged by her ex-boyfriend and an accomplice in 2008, has just had her 12-week scan, and excitedly confirmed the news in her column.
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"I'm so happy, and it's been really hard to keep it a secret," she wrote in The Sunday Mirror.
"It's funny that both myself and Simon Cowell, who is patron of my charity the Katie Piper Foundation, are going through the same experience. Perhaps the children will be playmates one day."
Katie and her boyfriend of two years moved in together last year, and had been trying for a child for months.
"I've always known that I have wanted children but there were moments after what happened to me that I never thought this would happen, I never believed this would be my future," she told The Mirror. "It's beyond incredible.
"It's because I'm so happy about it that it's been so hard keeping quiet and I'm actually relieved to be able to tell everyone. It's really nice to share this news with people who have given me so much support over the years."
Katie's fans were quick to congratulate the brave expectant mother, and the charity she founded, which supports acid burn victims, has asked for donations instead of gifts.
"Overwhelmed by all the congratulations tweets and best wishes! Thank you so much has completely taken my mind of todays morning sickness! X," wrote Katie.
Since her vicious attack, Katie has written several books about her story and featured in moving documentaries. The beautiful blonde is currently involved in Marks and Spencer's "Leading Ladies" campaign.