The idea, announced on Wednesday, will see AmEx customers check into Foursquare to find offers available from some of the UK's biggest retailers.
They will then "load" the special to their card via Foursquare, and automatically redeem it by paying with... American Express.
Customers will need no codes, coupons or other tokens to redeem the offers, and the balance from the special will show up on a customer's statement within five working days.
Among the launch deals are £10 cash back for a £10 spend at Bella Italia, Cafe Rouge, House of Fraser, Nando's, Pizza Express, Primark and Strada, and similar £5 deals at Tesco and Eat.
Stacy Gratz, VP and head of digital partnerships at American Express, said that while they did not have exact figures for how many of its card members had Foursquare accounts, there was enough overlaps to think it would be a success.
"There is a large overlap in the two profiles," she told the Huffington Post UK. "Foursquare users are slightly younger than the typical AmEx cardmember but they spend at roughly the same level."
In the US, where the partnership has been in place since June AmEx has redeemed "a couple of million" in deals she said.
The main benefit for customers - aside from the deals themselves - is the "seamless" nature of the transaction, she said.
Gratz added that Amex takes privacy "very seriously" and reassured customers that no personal data would be shared with Foursquare or retailers on an individual basis.
Evan Cohen, Foursquare COO, told the Huffington Post UK that despite some perceptions otherwise, Foursquare was growing rapidly in the UK - up to 70% more users and 50% more check-ins in 12 months, in fact.
"We wouldn't be here today if the UK wasn't one of our most important international markets," he said, adding that Foursquare recently opened an office in London - its first international site.
"Our mission has been to make the real life experience of our users more interesting and more fun. We help our users make the most out of their real-world experiences and this is a nice step in fulfilling that product and company mission."
Cohen said that while Foursquare adoption had been slower in the US that the UK - as the company's CEO Dennis Crowley said in March - but that the new partnership gave UK customers a "really exciting" reason to open the app and use it.
"We don't see the UK as performing any less well than any other markets," he said.
Even now it's a market in recession?
"I think this deal plays into that economic climate," he said. "We're offering a way to save money, and in difficult economic times customers are all the more interested and excited to find a way to save a few pounds here and there."
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