The new bottles contain 10%-recycled High Density Polyethelyne (HDPE) plastic material, manufactured from old UK milk bottles.
Previously, recyclable HDPE had to be imported from Continental Europe as there was no UK source. The conversion, to be rolled out over the next six months, will lead to all M&S milk bottles containing 10%-recycled content by October.
The move follows the conclusion of an M&S project undertaken with bottle manufacturer Nampak and recycler WES Greenstar to secure a UK source of recyclable HDPE.
Three billion HDPE milk bottles are used in the UK each year.
The energy saved in recycling one plastic bottle is enough to power a 60W lightbulb for six hours, manufacturers claim.