Millions of Barclaycard Visa credit card customers will be able to make "contactless" payments using the free PayTag sticker, which connects with special readers placed at shops, restaurants and transport to make payments.
PayTag is around one-third the size of a normal credit card and can be "discreetly" stuck to the back of any mobile phone, said Barclays.
The sticker can be used to make small payments of £15 and under, rising to £20 in June, by holding it over a contactless payment terminal.
This follows the launch of Barclays PingIt, a mobile app that allows users with any UK bank account to send money to anyone just by using their mobile phone number. Unlike PingIt, PayTag is only available to Barclaycard customers.
"Today, we are offering the choice of mobile payments to millions of our customers at no additional cost to them," said David Chan, the chief executive of Barclaycard consumer Europe.
"More than half of us say that the item we're most lost without is our mobile phone, so we're giving people the option of using them to make easy, convenient, everyday payments without the need to upgrade their current handset."
Contactless payment, either via mobile phones or special credit cards, is regarded by many as the future of how consumers pay for goods.
Research commissioned by Barclaycard has predicted that £3 billion worth of purchases will be made with mobile phones in the UK in 2016.
Payments firm Visa also expects the number of contactless point-of-sale terminals in the UK to increase by 50% to 150,000 this year.
They are already offered at various major chains, including Waitrose, McDonald's, Subway, Eat, Boots, WH Smith and Tesco, and by the end of 2012 all London buses will also accept contactless payments, followed by the Tube and the rest of the transport network in the capital in 2013.
Last week, Barclaycard announced a partnership with Orange to enable the mobile giant's credit and debit card holders from all UK banks to load money on the Barclaycard mobile payments app, and then use a Quick Tap wallet service for contactless payments. Orange said that Quick Tap will be launched on a range of Android smartphones in the coming weeks.
Concerns have been raised over security as the contactless payments do not always require a security identifier, such as a PIN number, meaning they could be exploited by fraudsters.
But Barclaycard claims that PayTag is "safe and secure" as it comes with 100% fraud protection.
"Barclaycard is developing a wide range of initiatives which will ultimately enable everyone to enjoy the benefits of mobile payments," said Chan.
"Barclaycard PayTag is another milestone on our journey to make paying easier, and sits alongside other easy ways to pay with your mobile such as those we offer in partnership with Orange."
Barclaycard customers can register to use PayTag by visiting the Barclaycard website. An exclusive group of customers will be invited to receive their PayTag in the coming weeks, before the stickers are offered to millions of Barclaycard customers later in the year, said Barclays.
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