The Irish star, 35, announced the news that she and Iain Stirling are expecting a baby in “early 2021” on social media.
In an Instagram post featuring a babygrow sporting the logo of American band Guns N’ Roses and the song title Sweet Child O’ Mine, she wrote: “I’ve always tried to be protective over the personal side of my life. A lot of things are just for me and my loved ones, and we’ve chosen not to share publicly.
“However I want to now share good news as it’s our news to share – and I’m gonna be honest it’s starting to look like my lockdown beer belly is out of control. Iain and I are expecting a baby early 2021. It’s been hard to keep such happy news quiet.
“Especially the times when I’ve had to run out of live radio to get sick in a bin or my penchant for a bowl of mashed potato in the morning.
“I wasn’t hungover like everyone thought. In fact I was completely sober filming the entire series of Celeb Juice, which is quite the accolade!
“We’d appreciate our privacy respected but just wanted to spread some love and a reminder of the beauty of life.”
Her post followed reports that she and Scottish comedian Stirling had got married recently.
Whitmore took over as the host of ITV2 dating show Love Island from Caroline Flack and also joined Celebrity Juice as a team captain alongside Emily Atack.
Stirling, who narrates Love Island, shared his own post about the announcement, posting a picture of his gaming consoles on Instagram with a note reading “I will miss you”.
He captioned the picture: “Sorry to my old babies but there is a new baby coming early 2021.”
Scarlett Moffatt was among the stars congratulating them, commenting on Whitmore’s Instagram post: “Congratulations to you both honestly you will make the most wonderful parents xxxx”.
Presenter Dermot O’Leary wrote: “The best news. Congrats x.”