The firm used social media and local outlets to drum up interest from customers in taking a ride in a karaoke cab that spent a day in Liverpool and a day in Manchester last week.
Content captured of its passengers will be published in the coming weeks across Instagram, Facebook, Youtube, Twitter, Snapchat and a specially designed microsite.
The cab was complete with a unicorn horn, and reflected the 'New Fashioned Christmas' concept created by Uniform, which is working on its inaugural project for Primark.
The New Fashioned Christmas theme is also replicated in store, with various images of models captured at a separate photoshoot.
There is no TV advertising accompanying the Primark campaign, a Uniform spokeswoman confirmed.
The first FAQ on the company's website explains that its low-advertising model is one factor in keeping its prices low, saying: "We also choose not to spend money on things that other retailers might. You might have noticed for example that we don’t do TV advertising or hardly any other advertising either."