Katie, 33, confirmed the happy news in an exclusive interview with HELLO! magazine, and couldn't contain her excitement about being pregnant again.
'Becoming a mum has enriched my life in ways I never imagined and I feel so thankful to be experiencing that again,' she told the title.
She added that the baby, who is due on New Year's Eve, will be a much longed-for addition to their family: 'I've been asked so many times if we were planning to have another child. The truth is, we were trying for about a year and a half, but that’s such a private and emotional thing when you’re going through it.'
The couple's three-year-old daughter Belle, meanwhile, has been busy getting ready to be a big sister, with Katie revealing that she's already been kissing her mum's tummy in preparation.
'I asked what she thinks I'm having and she said, "A girl, like me",' the mum-to-be said. 'I really don't have a preference, but I have a special bond with my own sister Suzy, who's also pregnant, so another girl would be lovely.'
'I know Richie would love a son to play football with, but, honestly, we're thrilled either way.'
Katie later followed up the article with a post to her Instagram account on Father's Day, sharing a picture from the shoot with the mag and writing: 'I'm so excited to tell you all next Father's Day my husband will be celebrating with two children!! Thank you @hellomaguk the beautiful photos will treasure forever! 🤰🏼👶🏾💕'
After the big reveal, fans rushed to congratulate Katie and Richard on the pregnancy, with one writing: 'So happy for all of you. What a joy it must bring to your lovely family', and another agreeing: 'Congratulations to you, your husband and Belle. Such lovely news for a lovely family.'
'Amazing news!!!' a third commented. 'Congratulations to you both. Praying blessings over you all.'