"Our press day tomorrow in the Marc Jacobs store is cancelled due to the theft of the spring/summer 2012 collections during its transfer from Paris," an e-mail sent from the fashion house to the media revealed.
London's Metropolitan police force confirmed on Thursday it was investigating the case.
"The theft was reported to police, via telephone, after a quantity of clothing, bags and shoes reported to be worth £40,000, ($63,000) were found to be missing earlier in the day," a police spokeswoman said.
"Officers based in Westminster are investigating."
The items were stolen from a delivery van outside Jacobs's store in the exclusive London neighbourhood of Mayfair.
The range, which included drop-waist skirts, cellophane cocktail dresses and translucent and tinsel fabrics, was due to go on show on Friday.
The pieces, which were transported by train from Paris to London, have little street value as they are only samples from next season, raising suspicions that counterfeiters were behind the incident.
The theft deprives British fashion editors of the chance to sample next year's products, putting the Paris-based firm on the back foot.
It is another blow for Jacobs, who last week had his perfume advertising campaign -- featuring 17-year-old Dakota Fanning -- banned following accusations that it sexualised children.