Guardian readers have been opening their weekend paper to find supplements wrapped in a compostable material made from potato starch.
The paper says it ditched its polythene covers after feedback from readers.
Advice on the wrapping says it should not be recycled but disposed of on a compost heap or in a food waste bin.
The change, which the Guardian says will increase its production costs, has been introduced in London, Kent, Essex, Hertfordshire, Norfolk and Suffolk.
It plans to phase in the new wrapping across the whole of the UK over the coming months.
The packaging, produced by environmental manufacturer Ecover, has a silky feel and is not entirely transparent like plastic.
The company has received the composting seal of approval from OK Compost Home, which certifies products.
The Guardian said the wrap was suitable for domestic composting and designed to "completely compost within six months in a well-maintained compost heap or food waste bin".
The Guardian said it would not reveal the extra cost involved in switching to the packaging.
Other publications have already moved to potato starch wrapping, including the New Internationalist and the National Trust members' magazine, but the Guardian says it is the first national newspaper to do so.
Other national newspapers say they have been experimenting with more environmentally-friendly ways to distribute their magazines, supplements and advertising leaflets.
The Times said it was trialling biodegradable bags and "belly bands" - a looped strip of paper - and hoped to roll out at least one of these options "as soon as we can".
A spokesman for the Mail on Sunday said: "We are actively investigating an alternative to polythene bags, in particular using a form of paper packaging."
The FT said it removed all plastic packaging of home deliveries at the start of the year - and papers sold in newsagents and supermarkets have always been unwrapped.
The move at the Guardian coincides with a 30p price hike of the Saturday edition to £3.20. The price of the weekday edition and the Observer are also going up by 20p, to £2.20 and £3.20 respectively.
What is potato starch packaging?
Usually comes from waste potatoes so you don't need to grow a crop to make it 100% compostable
Contains no oil-based materials, plastics or harmful toxins
Carries the EN13432 industrial certification. OK compost HOME certification, which the Guardian wrapper has, is the equivalent for domestic compost