Customers will be given M&S store vouchers for their loyalty and as incentives to encourage them to cut energy use. SSE hopes that teaming up with the retailer will provide access to new customers.
The venture will charge an average £1,196 per year for the standard "dual fuel" tariff bill (including VAT) - the same as it costs SSE customers.
The electricity used by M&S Energy customers will be secured by SSE from large-scale hydro sources in Scotland.
Users who reduce annual energy usage by 10% in the first year will get a £15 M&S voucher and those who choose paperless billing will receive an additional £10 voucher.
Dual fuel customers switching to M&S Energy will also get a £20 Marks & Spencer voucher on signing up and a further £10 voucher for each year they stay with the supplier.
M&S Energy launches in 16 M&S stores and online on October 27. It will be extended to 62 stores nationwide by the end of November.
Scott Byrom, utilities manager at moneysupermarket.com said, "M&S is a trusted brand and is offering vouchers for people to switch. But consumers need to think past the incentive and about real savings.
"Standard rates tend to be the most expensive and least competitive, while online deals are the cheapest around and fixed rates offer peace of mind."