The film is called "Britain prepare for zombies: only humans allowed". It features zombie incarnations of a businessman, a tourist, a delivery man, a street sweeper and a policewoman walking across a city to a Greggs, where they attempt to walk inside, leaving screaming consumers in their wake.
The Greggs' store manager pushes the zombies out of the shop with a broom, telling them the shop has nothing to offer them.
The ad then drives consumers to Greggs Facebook page, which will update consumers about future sightings of the zombies.
The digital work is supported by 14 sampling events across the UK over the next few weeks, touting the retailer’s range of "pumpkin doughnuts" and "spooky ringbuns".
Consumers who upload pictures of themselves with the zombies onto Facebook will be entered into a larger prize draw being run by the brand.
Greggs worked with agencies Irresistible Films, Gatterpalm, Steel and Havas PR UK on the campaign.
In August Greggs ran a campaign to find its most passionate fans via social media that offered consumers the chance to win a free lunch every week for a year.