Talerddig Bakery, based near Llanbrynmair, is well known in the area, providing its bakes to shops, hotels and cafes.
It also has three shops and employs 20 people, including bakers, shop assistants and delivery drivers.
Talerddig is being sold as a business with its equipment and delivery vehicles.
Kathryn Evans, of estate agents Morris, Marshall and Poole, said: "Anyone driving along the main A470 will see the bakery at the side of the road in Talerddig or have seen its bread, cakes and other products in shops, cafes or homes throughout the area."
The business was set up by Tom and Margaret Lewis at the current site in 1925. It was then taken over and expanded with a new bake house commissioned and opened in 1979.
It was then passed down to the Thomas', bakers from Machynlleth, who sold it in 2013 to current owner Steve Jones.
The business has three shops at Llanidloes, Machynlleth and Borth.
A family bakery which started baking bread 90 years ago in Powys has been put up for sale.