Retailers including Cadbury and Selfridges will have to re-apply for permission to use the Royal Arms in association with their products.
More than 100 food and drink brands have had a Royal Warrant of Appointment, providing them with permission to use the imagery on their packaging.
After Queen Elizabeth II’s death on Thursday last week, these warrants have become void.
Brands will have two years to stop using imagery of the Royal Arms or have to reapply for a warrant from King Charles III.
This impacts a range of household names, including Cadbury, Unilever and Britvic.
Within their applications for a new warrant, brands must be able to show evidence they supply “products or services on a regular and on-going basis to the Royal Households of grantor/s for not less than five years out of the past seven,” according to the Royal Warrant Holders Association.
Companies will also need to prove they have “an appropriate environmental and sustainability policy and action plan.”