The former glamour model turned reality star, 45, was caught on camera having a puff.
Katie was live on TikTok giving fans a behind-the-scenes look at her dressing room as daughter Bunny held her phone.
However, during the stream as production put the finishing touches to Pricey’s outfit she took out her vape.
Stunned Katie then realised she had been caught as she quickly put away the e-cigarette before turning her head and exhaling.
The mum-of-five now risks being fined £5,000 as the law states it’s illegal to smoke or vape in ‘music and sports venues’.
Katie, who is starring The Wicked Fairy Carabosse in Sleeping Beauty at the M&S Bank Arena in Liverpool, also risks being thrown out of the theatre.
Bosses have a strict zero-tolerance policy on the use of smokes and e-cigarettes at the venue.
They state on their website: “Smoking is strictly prohibited. Anyone found smoking anywhere within the venue will be requested to leave without refund.
“The use of electronic cigarettes is also strictly prohibited.”
It comes after panto organisers reduced ticket prices in the wake of Katie receiving scathing reviews from some audience members.
The former Celebrity Big Brother winner, who is said to be earning £60,000 for the gig, was branded a “disgrace” and accused of failing to memorise the pantomime’s dance routines.
Her co-star has even claimed she has “learned two of her 25 lines”.