Speaking after his winner’s performance, the south London star, whose full name is David Orobosa Omoregie, said his win was “the biggest compliment” and “way bigger than me”.
The 21-year-old picked up the gong for his number one debut album Psychodrama, which was released in March, beating acts including Foals, The 1975 and Anna Calvi to the prize.
Judges described the album as “the musical equivalent of a literary masterpiece” which would have “lasting relevance for a generation”.
On stage, he also thanked his brother Christopher Omoregie, who was jailed for life in 2012 for a knife murder, and said the story of Psychodrama was inspired by therapy his sibling received.
Dave said: “I want to thank God. I want to thank everyone, my mum.
“I want to thank my brother Christopher. Even though you can’t be here with us today, I know you are watching this bro.”
Born in London to Nigerian parents, Dave is the youngest of three brothers.
His two older siblings have both served time in prison, which the rapper alludes to in his music.
After his album reached number one in the charts earlier this year, he made headlines again at this year’s Glastonbury, when he invited teenager Alex Mann to join him on stage to rap along to his hit Thiago Silva, and the clip went viral.
Along with slowthai and Idles, he had been one of the bookies’ favourites to win the Mercury Prize.
Speaking after the ceremony at the Eventim Apollo in Hammersmith, west London, Dave paid tribute to all the “talented artists” who were up for the award, as well as the “unsung heroes” who work with him, and said: “I never expected to win…
“It’s the biggest compliment, it is the biggest compliment, and this is an award that is all about the music.”
He added: “This is probably the best day of my mum’s life, my brother’s too. It’s crazy times now.”
The Mercury Prize is awarded for the best album released in the UK by a British or Irish act and also has a winning cheque for £25,000.
Dave’s win was not the only talking point of the night, with fellow award nominee and rapper slowthai also making headlines thanks to his performance.
At the end, he punched the air with a dummy severed head of the prime minister, before shouting, “f*** Boris” and adding, “there’s Nothing Great About Britain” – the title of the album he was nominated for.
The audience responded with rapturous applause as he left the stage.
During their performance, Foals held up a climate change banner which read: “No music on a dead planet”.
Twelve acts were shortlisted for the 2019 Mercury Prize.
The other nominees were Little Simz, NAO, black midi, Cate Le Bon, Fontaines DC, Idles and Seed Ensemble.