Gok Wan, George Clarke, Anna Richardson and Ade Adepitan feature in an ad talking about their favourite small shop, celebrating the "hidden gems" on UK high streets.
It will launch during Humans on 4 December on Channel 4. The ad will run until 18 December on Channel 4, More 4 and All 4, the video on demand service.
Sassy Films created the film, working with Mindshare and Ogilvy & Mather.
There will also be a hashtag #ShopSmallUK on social media, and viewers will be directed to amexshopsmall.co.uk to find out their local small businesses.
Alice Noone, vice president for partnerships and brand at American Express, said: "At American Express, we have a long history of supporting small businesses and celebrating their dedication to their customers.
"In 2016, Shop Small continues this great tradition by uncovering the amazing and unique hidden gems that can be found all over the UK."