The Barista app - which is currently only available across selected stores in London-, will be rolled out across the UK "as soon as possible", M&S said.
Developed to enable shoppers to collect points "on the go", it offers "exclusive" special offers and benefits and can be used at M&S Cafes and Hot Food on the Move counters across the capital to drive brand loyalty and repeat purchase.
It will enable M&S to better compete with other grocers, as well as the likes of Starbucks, Pret a Manger and Costa Coffee.
Developed by Eagle Eye and fit with a store finder tracker, it hosts hot food and drink offers. Customers get the sixth coffee they buy for free.
M&S senior marketing manager Matthew Legge said: "We are focused on providing our customers with excellent quality, value for money and convenience.
"The trial of a digital loyalty card in our Hot Food on the Move and Cafes will further help us meet those aims, whilst rewarding our customers for their loyalty."