The band was due to perform at the event in Suffolk, England on Friday (18Jul14), but they pulled out after frontman Alex Trimble collapsed at an airport in Seattle, Washington while en route to London and was hospitalised with a stomach condition.
Allen has now offered to take over their slot at the festival on Friday, marking her debut at the event just weeks after she performed a huge set at Britain's Glastonbury festival.
The singer says in a statement, "So sorry to hear about Alex from Two Door Cinema Club. However, I am more than happy to step in. I've never been to Latitude but I hear it's fabulous and I can't wait to get my heels on for some serious dancing action on Friday evening - so, so excited."
Other acts performing at the event across the weekend (19-20Jul14) include Blur star Damon Albarn and The Black Keys.