The 'Not Fair' singer has often been tipped for a place on the show's panel and has most recently been rumoured as a possible replacement for Dannii Minogue at this year's auditions.
A position on The X Factor would have seen the 25-year-old working alongside Cheryl Cole following their long-running war of words.
However, speaking to the Sunday Mirror, Allen commented: "I won't be a judge on X Factor. That's so not the sort of thing I'd do.
"But I wouldn't have a problem sitting next to Cheryl. There's no feud. I have nothing bad to say about her. Her song 'Parachute' is genius and it's on my iPod."
Geri Halliwell filled in for Minogue at X Factor auditions in Glasgow last week, while Natalie Imbruglia has taken her spot in Birmingham over the past two days. Meanwhile, Katy Perry and Pixie Lott have been confirmed as future guests.