It’s the only time the presenter – who hosts Britain’s Got More Talent – has not been able to attend filming in 11 years.
In a tweet, 40-year-old Stephen told his fans he’d been put on bed rest by his doctor after falling ill.
Stephen said: “Morning! Absolutely gutted to be missing the first round of @BGT auditions this week in Blackpool!
“I am on doctor’s strict orders to rest my voice, after suffering a nasty bout of Laryngitis - first day off from the show in 11 years. Unbelievable!
“I will be on mute until London auditions on the 27th Jan, look forward to seeing you all then!”
Stephen’s followers inundated him with messages of support after he broke the news.
One tweeted: “Get well soon. I’m sure you’ll be missed there, as much as you’ll be missing it too.”
A second told him: “I hope you feel better soon. Sending love.”
Morning! Absolutely gutted to be missing the first round of @BGT auditions this week in Blackpool! I am on doctor’s strict orders to rest my voice, after suffering a nasty bout of Laryngitis - first day off from the show in 11 years. Unbelievable! (1/2)— Stephen Mulhern (@StephenMulhern) January 16, 2018
Stephen has worked on the hit ITV show since 2007 and admitted he loves working with Simon Cowell, David Walliams, Alesha Dixon and Amanda Holden.
Speaking about working with X Factor mogul Simon, Stephen previously told Now Magazine: “He’s always been a hard boss but since his son Eric was born he’s been chilled.
“For me it’s the biggest joy I was like: ‘OMG, thank you!’ He’s a different person, he really is.”
The show will start later this year with a whole host of talented individuals hoping to impress the judges.
Last year's winner Tokio Myers went on to sell out the Albert Hall following his success in the competition.
He's gone on to release an album and performed during The X Factor final.