The eight brushes which the Irish-born painter gave to fellow artist Clive Barker in 1978 are in a paint-splattered butter bean tin encased in a perspex box.
They will be auctioned at Christie's in South Kensington, London, in September as part of its Out of the Ordinary sale.
Dublin-born Bacon, who died in 1992, is one of the most sought-after modern artists.
Last month, his 1966 triptych portrait of his friend, muse and lover Isabel Rawsthorne went for £11,282,500 while the first work the artist ever sold, his historic Head III, went for £10,442,500.
More than 150 lots will be auctioned off including a flying machine prop made for the 1985 Young Sherlock Holmes film which is expected to fetch £80,000, a Triceratops skull valued at £250,000 and one of the world's biggest caviar dishes.
Head of sale Charlotte Young said: "Out of the Ordinary is a tightly curated one-off sale offering a unique opportunity to acquire something a little different from Christie's South Kensington. Each lot has been selected as either visually striking or with an intriguing story to tell, and many have never before been seen at auction.