The New Wilderness by Diane Cook, Tsitsi Dangarembga’s This Mournable Body, Douglas Stuart’s Shuggie Bain and Real Life by Brandon Taylor are also up for the award.
Dame Hilary Mantel, who featured on the longlist, has failed to make the cut and missed out on becoming a triple winner of the prize with the third book in her Cromwell trilogy, titled The Mirror And The Light.
Commenting on her omission, judge and author of the Jack Reacher series Lee Child said the panel thought it was “an absolutely wonderful novel”.
He said her trilogy of novels is “one for the ages”, but added: “There were books that were better, that’s all I can say personally.”
The shortlist features four women and two men. Cook, Stuart and Taylor are also debut novelists.
The shortlist, announced at a digital press conference on Tuesday, was chosen by a panel of five judges – literary critic Margaret Busby, authors Child and Sameer Rahim, writer Lemn Sissay and classicist Emily Wilson.
Busby, chairwoman of the judging panel, said: “As judges we read 162 books, many of them conveying important, sometimes uncannily similar and prescient messages.
“The best novels often prepare our societies for valuable conversations, and not just about the inequities and dilemmas of the world – whether in connection with climate change, forgotten communities, old age, racism, or revolution when necessary – but also about how magnificent the interior life of the mind, imagination and spirit is, in spite of circumstance.
“The shortlist of six came together unexpectedly, voices and characters resonating with us all even when very different.”
Burnt Sugar tells the story of the shifting power dynamics in a mother-daughter relationship when the parent, who previously enjoyed a wild life, is forced to let her child look after her as she gets older.
The Shadow King is about an orphan living in Ethiopia amid the threat of invasion by Mussolini.
The winner will be announced on November 17.
The shortlisted authors each receive £2,500 (€3,700) and a specially bound edition of their book, while the winner receives a further £50,000 (€54,000).
Last year’s prize was jointly won by The Testaments by Margaret Atwood and Girl, Woman, Other by Bernardine Evaristo.
Commenting on whether there would be multiple winners this year, Sissay said: “If we wanted to have a joint win or a triple win we could have gone for it.”
He added: “But rules are there to be broken, aren’t they? Because that’s what they did last year.”
Evaristo praised the shortlist on Twitter, saying she is “so excited by this groundbreaking shortlist for the 21st century”.
She wrote: “It’s all about who’s in the room and the value they place on different kinds of literature.
“If you’re looking for fresh perspectives and narratives, surely you’re going to find it among the most under-represented voices?”
Last month Dutch author Marieke Lucas Rijneveld was announced as the winner of the International Booker Prize for The Discomfort Of Evening.