Booker Prize winner Douglas Stuart says his victory “means a lot” for regional voices and working-class stories.
The Scottish writer was chosen unanimously by this year's judges to win the award.
The 44-year-old was announced as the prize during a virtual ceremony which featured a contribution from former US president Barack Obama.
Shuggie Bain, which is based on Mr Stuart’s childhood, is set in Glasgow in the 1980s and tells the story of a young boy growing up with a mother who is battling addiction.
The author explores poverty, tough upbringings and alcoholism in his book.
In his acceptance speech, Stuart said: “I know I’m only the second Scottish book in 50 years to have won and that means, I think, a lot for regional voices, for working-class stories, so thank you.
“Thank you to the people of Scotland, especially Glaswegians, whose empathy and humour and love and struggle are in every word of this book.”
He added: “To all the readers who have just come out and let me know that Shuggie and Agnes have touched their lives, I can’t believe this, but the greatest gift is just to be able to connect with you.”
He also thanked his late mother, who died when he was 16, after being announced as the winner of the prize.
“My mother is in every page of this book and without her, I wouldn’t be here and my work wouldn’t be here.”
Mr Stuart said she “would be proud” and “thrilled” about his achievement.
He added that the prize has “changed my entire life”.
Mr Stuart, who works in fashion in the US, said: “I always wanted to be a writer, so this is about fulfilling a dream that was furloughed.
“Young boys like me growing up in 80s Glasgow, this wasn’t anything I ever would have dreamt of and, in fact, I was sort of turned away from English and academia towards textiles, which was a much more employable trade.”
Margaret Busby, chair of the judging panel, described Shuggie Bain as “daring, frightening and life-changing”.
She added: “The heart-wrenching story tells of the unconditional love between Agnes Bain – set on a descent into alcoholism by the tough circumstances life has dealt her – and her youngest son.
“Shuggie struggles with responsibilities beyond his years to save his mother from herself, at the same time as dealing with burgeoning feelings and questions about his own otherness.
“Gracefully and powerfully written, this is a novel that has impact because of its many emotional registers and its compassionately realised characters.
“The poetry in Douglas Stuart’s descriptions and the precision of his observations stand out: nothing is wasted.”
The shortlist for the £50,000 prize also featured Avni Doshi’s Burnt Sugar and Maaza Mengiste’s The Shadow King.
The New Wilderness by Diane Cook, Real Life by Brandon Taylor and Tsitsi Dangarembga’s This Mournable Body were also nominated.
Mr Obama addressed the ceremony via a pre-recorded video message.
“I’ve always turned to writing to make sense of our world… and at their best Booker Prize-listed books remind me of fiction’s power to put ourselves in someone else’s shoes, understand their struggles, and imagine new ways to tackle complex problems and effect change,” he said.
“I want to salute the work of the Booker Prize Foundation to encourage people to read more fiction and promote the art of reading for the public benefit.”
Stuart is the second Scottish writer to win the award after James Kelman scooped the 1994 prize for How Late It Was, How Late.
Ms Busby was joined on the judging panel by writers Lee Child, Sameer Rahim and Lemn Sissay, as well as classicist Emily Wilson.
Last year’s prize was jointly won by Margaret Atwood’s The Testaments and Bernardine Evaristo’s Girl, Woman, Other.
The Booker Prize, first awarded in 1969, is open to writers of any nationality whose work is written in English and published in the UK or Ireland.