The lingerie set has been made at a plant Sri Lanka that has cut energy use by a third, maximised sunlight and using low energy bulbs, Britain's Telegraph newspaper said.
The rest of the carbon dioxide produced in making the bra will be offset by planting 6,000 trees every year, the report said.
Mike Barry, head of sustainable business at M&S, said the retailer will try to make more clothing carbon neutral in future.
"We don't want green, eco-friendly products to be in a ghetto in the corner, we should be making all products more environmentally friendly," he was quoted as saying by the Telegraph.