The girl group - who are celebrating their 10th anniversary this year - are said to have reunited to film a video for the comeback track on Tuesday (October 2), according to The Mirror.
"The girls recorded tracks with their long-time collaborators Xenomania as early as May this year," a source claimed.
"Some of them recorded their vocals separately, so they didn't actually see each other that much during the process. Obviously, Nadine [Coyle] has been pretty estranged from the group during their time off, too.
"But on Tuesday, all five were together to film the video for their big return song, which is due out next month.
"It was the last possible opportunity they would all have to get together in time for the release, as Cheryl [Cole] has been busy rehearsing for her tour and Kimberley [Walsh]'s training schedule for Strictly has been getting more and more intense."
Nicola Roberts recently stated that Girls Aloud would be marking their 10th anniversary in some form in November.
Cheryl Cole has also hinted at possible new Girls Aloud lyrics, stating "I just wanna dance" during an interview in August.
Watch the video for 'The Promise' by Girls Aloud below: