A total of 1,400 Oliver Bonas dresses were stolen from a lorry in Gravesend, Kent.
The dresses were stolen from the lorry while it was parked in an Asda car park in Imperial Retail Park in Thames Way, Gravesend.
All dresses were of the same design – navy with a white and grey print.
The incident reportedly happened on 17 January and police are appealing for witnesses.
A spokeswoman for the retailer said: “All 1400 units of one of our dresses, designed by our in house team at Oliver Bonas, were stolen on route to our warehouse just days before they were due in store. We encourage anyone with any information to contact the Kent Police.”