CD versions of the X Factor winners' LP DNA were snapped up by fans as part of Amazon's Black Friday Deals Week.
The units were delivered to Amazon's Hemel Hempstead warehouse by the band on Monday (November 19) and went on sale for £3.99 this Wednesday (November 21).
The super-quick sell out beat a previous record set by One Direction; 500 signed copies of the boyband's debut album Up All Night sold out in under a minute as part of the same promotion last year.
"The girls are ahead in the Black Friday popularity stakes," said John Boumphrey, Director of Music, Film and TV at Amazon.
"[But] with 500 signed copies of One Direction's new album Take Me Home still to run as a Black Friday deal today (November 23), the battle of the pop bands is still to be decided."
Little Mix are predicted to enter this week's album chart at number four, trailing behind Rihanna, Led Zeppelin and One Direction.
Watch the video for the girlband's latest single 'DNA' below: