He was chosen as victor from the most diverse shortlist in the prize's five-decade history. The Novel goes back to 1980 at Glasgow, where a young boy is trying to support his mother as she struggles with addiction and poverty.
Shuggie Bain follows Shuggie as he attempts to care for his alcoholic mother, Agnes, whose descent into alcoholism coincides with her youngest son's growing awareness of his sexuality. After graduating from the Royal College of Art, he moved to NY to start a career in fashion design, working for brands including Calvin Klein, Ralph Lauren and Gap.
He described the book as a "love story" looking at the kind of "unconditional, often-tested love" that children can have for flawed parents.
"Shuggie Bain" is Stuart's first novel. Despite its grimness and squalor, the book - dedicated to the writer's mother, who died when he was 16 years old - brims with tenderness and filial affection.More news: Tigray forces fire three rockets into neighbouring region of Ethiopia
Post-win, he says full time writing is now on the cards for him, and he might use his prize money to return to Glasgow.
On this occasion, former US President Barack Obama also expressed his views on the booker award-winning novels.
Margaret Busby, this year's chair of judges, spoke briefly before announcing the victor, stating that the vote for Stuart's Shuggie Bain was quick and unanimous.
"I always wanted to be a writer so this is fulfilling a dream".
Also on the list is Zimbabwean writer Tsitsi Dangarembga's "This Mournable Body", which links the breakdown of its central character and turmoil in post-colonial Zimbabwe.More news: Time To Watch The June 2020 Strawberry Full Moon In Florida
The novel has drawn comparisons to D.H. Lawrence, James Joyce and Frank McCourt- It has been a favourite contender for this year's top literary prizes, being also a finalist for the Kirkus Prize and the National Book Award for fiction, which on Wednesday went to Charles Yu for "Interior Chinatown".
Stuart's book won from a shortlist that was notable for having four debut novels, and no "big names".
Obama addressed the ceremony via a pre-recorded video message tonight. "We sit alone in a room for a long time and write, and then people sit alone in a room and read it".
Judges previous year tore up the rule book by awarding it jointly to Canadian author Margaret Atwood and Anglo-Nigerian author Bernardine Evaristo.
First awarded in 1969, The Booker Prize is considered one of the leading prizes for literary fiction written in English.
"Reading lovely works of fiction late at night, by Booker Prize-listed authors like Marilynne Robinson, Colson Whitehead, Bernardine Evaristo and so many others, offered me a brief respite from the daily challenges of the presidency".More news: Rebekah Vardy wins first round in â€˜Wagatha Christieâ€™ libel battle