The 30-year-old TV presenter and model had her 12 week scan last week accompanied by her boyfriend of two years.
In 2008, Katie had been working as a model when jealous ex-boyfriend, Daniel Lynch, arranged for acid to be thrown in her face.
Katie said of the happy news: "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."
Speaking to The Sunday Mirror, she added: "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."
In her column for today's Sunday Mirror, glowing Katie added how happy she was to share the experience with music mogul Simon Cowell, who is patron of her charity for burns victims and soon to become a first-time father with pregnant girlfriend Lauren Silverman.
She wrote: "I'm very excited to share my news that I'm going to be a mummy.
"I'm so happy, and it's been really hard to keep it a secret.
"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.'
Fans have already reacted to the good news on Twitter, prompting Katie to reply she has been "Overwhelmed by all the congratulations tweets and best wishes! Thank you so much has completely taken my mind of todays morning sickness! X"
Her heart-warming news is in stark contrast to her horrific ordeal five years ago, when violent ex-boyfriend Lynch raped Katie and held her captive in a London hotel for eight hours.
But his revenge continued two days later when, under his direction, accomplice Stefan Sylvestre threw a cup of industrial-strength sulphuric acid in her face.
The attack on a London street melted her face, blinded her in one eye and left her with horrific burns.
Rushed to the burns unit of Chelsea and Westminster Hospital, Katie was showered with tap water for 10 hours as medics fought to neutralise the effect of the acid on her skin and prevent further damage. Eye drops were also administered every few minutes to try to wash the acid away.
The left side of Katie's face was burned away to the fat layer - the only thing beyond it was muscle and bone.
She lost the sight in her left eye and acid also dripped down her neck, ears and hands as well as slipping into her nose and throat, with further terrible consequences.For more than a year she had to be fed through a tube in her stomach and surgery to dilate her oesophagus. In total, she has endured more than 40 operations since the attack.
As well as the physical damage, the attack left Katie fearful of going out in public and her self-esteem was destroyed as she hated seeing her scarred face. She had to cover her face with a protective mask for two years.
In May 2009, Lynch and Sylvestre were told by the judge that they were 'the face of pure evil'.
Both were jailed for life and Lynch will serve a minimum of 16 years.
Katie, from Andover, Hampshire, has since bravely rebuilt her life and turned her experience into something positive.
She has won widespread support for her series of thought-provoking documentaries for Channel 4, written three books about her experience and has won awards - including Woman of the Year in 2011 and a Pride of Britain award.
Recently, Katie was also revealed as one of the new stars of the Marks & Spencer campaign, appearing alongside actress Helen Mirren, artist Tracey Emin and British female boxing champion Nicola Adams.