The former pop star, who is playing Katurian in the revival of Martin McDonagh’s 2003, was forced to leave the matinee production along with the rest of the show’s cast and crew.
All audience members were also escorted outside the London theatre as a fire engine arrived at the scene amid the emergency.
A spokesperson for the London fire brigade confirmed that they were called to the scene where they discovered it had been a false alarm.
They told The Sun: “The theatre was evacuated as a precaution. A crew attended and following investigation, established there was no fire.
“The brigade was called at 3.11pm and the incident was over for firefighters by 3.24pm.”
Following the false alarm, audiences were eventually able to re-enter the theatre and the performance resumed.
While waiting outside, several theatre-goers shared their confusion over the emergency on social media platform X, formerly known as Twitter.
One person wrote: “Right in the middle of a gripping performance of The Pillowman at the Duke of York’s Theatre, we were evacuated.
“Fire brigade showed up a few minutes later. Not sure why yet, but the spell is broken, I’m afraid.”
Right in the middle of a gripping performance of the Pillow Man at the Duke of York’s Theatre, we were evacuated.
Fire brigade showed up a few minutes later.
Not sure why yet, but the spell is broken I’m afraid. pic.twitter.com/luUzEeR5IE
— Richard Banks (@RichardBanks_) August 23, 2023
While another wrote: “Finally got to see @SP1nightonly on stage this afternoon in The Pillowman.
“Unfortunately during act 1, it seems like everyone who is in a building in St Martin’s Lane got evacuated out to the street with fire engines turning up from @LondonFire”
“Lovely time at the pillowman today (we got evacuated)” a third commented.
This isn’t the first time the theatre show experienced an emergency during a performance after Allen paused the play after noticing that an audience member had collapsed during her monologue earlier this month.
The Smile hitmaker reportedly noticed the woman falling ill and raised the alarm. The production was allegedly halted for 30 minutes before the performance resumed.