Shuggie Bain was inspired by Stuart's own childhood, growing up in gay and in poverty in the 1980s in Glasgow, while being raised by a mother struggling with addiction. He was awarded the 2020 Booker Prize for Fiction on Thursday.
Stuart won the prestigious 50,000 pounds ($66,000) award on Thursday for his first published novel.
The victor of this year's Booker Prize is Douglas Stewart for his debut novel, Shuggie Bain.
Stuart is the second Scottish writer to win the award after Kelman scooped the 1994 prize for How Late It Was, How Late.
She called it intimate and gripping, challenging but hopeful in its exploration of young Shuggie's complex but loving relationship between mother and son.
Stuart dedicated the novel to his late mother, who died of alcoholism when he was 16.
"My mother is in every page of this book, and without her I wouldn't be here and my work wouldn't be here", said Stuart, who declared himself "absolutely stunned" to win.
She said: 'I'm so thrilled for Douglas Stuart - Shuggie Bain is a raw, searing and beautifully tender novel.
Actor Paapa Essiedu read from finalist Brandon Taylor's "Real Life" at the virtual 2020 Booker Prize ceremony.
"Working-class Scotland was hard for them", Stuart said. He said his victory was a sign that "we are starting to hear and be able to respect diverse voices". In contrast, the United Kingdom ceremony maintained some live elements, taking over the Roundhouse performance venue in London, which for the hour-long event was populated only by the host, British journalist John Wilson; previous victor Bernardine Evaristo; judges chair Margaret Busby and the four-piece Chineke!
"It's hard to come away from that book without thinking 'This is going to be a classic, '" she said.
Previous year the honour was conferred jointly to Atwood for The Testaments and Evaristo for Girl, Woman, Other.
Busby was joined on the judging panel by writers Lee Child, Sameer Rahim and Lemn Sissay, as well as classicist Emily Wilson.
Stuart was chosen from a shortlist dominated by USA -based writers from diverse backgrounds.
The coronavirus pandemic scuttled the Booker's traditional black-tie dinner ceremony at London's medieval Guildhall.
Special guests included novelist Kazuo Ishiguro, victor of a Booker and the Nobel Prize in literature; Camilla, Duchess of Cornwall; and former U.S. President Obama, whose memoir "A Promised Land" hit shelves Tuesday and sold almost 890,000 copies in the U.S. and Canada on its first day.
'For all these reasons, this year's Booker Prize is even more important than usual.
Stuart was one of four debut novelists among the six shortlisted for the prize. Mantel won the Booker for both its predecessors, "Wolf Hall" and "Bring up the Bodies", and had been widely tipped for the hat trick.
Paul Beatty became the first American victor when the Booker bowed to pressure and began including authors from outside the Commonwealth, Ireland and Zimbabwe in 2013. There have been two American winners, Paul Beatty's "The Sellout" in 2016 and George Saunders' "Lincoln in the Bardo" in 2017.
That year's change sparked fears among some Britons that it would become a U.S-dominated prize.