Slowthai said he does not condone violence, after posing with an effigy of Boris Johnson’s severed head.
The rapper held the head aloft during his performance at the Mercury Prize ceremony in London.
After an energetic act he proclaimed, to cheers from the audience: “F*** Boris Johnson. F*** everything.”
The artist, whose record Nothing Great About Britain was nominated for the prestigious album award, has said his act was merely metaphorical, and said he does not advocate violence.
Explaining his actions, the 24-year-old said on Twitter: “This ‘act’ was a metaphor for what this government is doing to our country, except what I did was present it in plain sight.
“No Boris Johnsons were hurt in the making of this slowthai performance.
“I don’t condone violence in any form.”
In a statement posted online, he further said: “Last night I held up a mirror to this country and some people didn’t like the reflection.
“The people who isolate and divide us aren’t the ones who will feel its effects the hardest.
“They’re not the ones queuing at food banks, no the ones navigating Universal Credit and not the ones having to deal with systematic oppression and hate crime at the hands of privileged politicians who say what they want without fear and consequence
“We as a people are not being looked after and our best interests are not being served by those in government – this is their job and they’re not doing it well enough.”
He was met with rapturous applause and cheers from the audience assembled at the Eventim Apollo in Hammersmith on Thursday.
He lost out to London-born rapper Dave, who claimed the coveted Mercury Prize for his work Psychodrama.
Stormzy was among the judges who decided the winning album. He made headlines at the 2018 Brit Awards for his on-stage criticism of Theresa May.