The organic sandwiches will be stocked in Waitrose stores in London as well as the food hall in John Lewis on Oxford Street, before a nationwide roll-out.
Fillings for the sandwiches include smoked mackerel and cheddar cheese. They also use Duchy Originals ingredients, such as tomato relish, contain no artificial additives or preservatives, and are handmade using bloomer loaves created for the range. Prices start at £2.99.
The brand's growing portfolio also includes a range of garden tools and hair and body products.
Duchy Originals was launched in 1992 with an Oaten Biscuit product and was a pioneer in pushing provenance and organic ingredients. It is a not-for-profit business, and has generated more than £6m for charitable causes since its launch.