Group chief executive officer Roger Holmes said the conversion of 2.3 million existing chargecard holders could help make the new card the UK’s seventh biggest credit card scheme by November.
Three retailers currently issue credit cards - the Co-operative Group’s partner the Co-operative Bank has 1.55 million holders, and is ranked the highest by Datamonitor in ninth place overall.
Tesco Personal Financial Services is at number 12 with one million accounts and Sainsbury’s Bank, in 13th place, has 649,000 holders.
M&S will put point-of-sale up in all stores, including Simply Food stores, when it launches &more on October 6. There will also be a TV advertising campaign based on Dean Martin’s hit song That’s Amore.
The &more card offers 1p back on every £1 spent in M&S and 1p on every £2 spent elsewhere, issued as quarterly M&S vouchers.
It said the move was prompted by a general decline in the use of storecards in the retail sector.
A spokesman said it was too early to say if the credit card would have a loyalty element.