Jamal Edwards, the founder of the online music platform SBTV, which launched the careers of artists including Ed Sheeran, Jessie J and Skepta, has died aged 31.
The YouTube star and entrepreneur's company confirmed the death to the BBC, but his cause of death is unclear.
Edwards performed as a DJ at a gig in London on Saturday night, according to the British broadcaster.
"No details have been released about his death, other than it happened on Sunday morning," the BBC reported.
His last Instagram post was late last week, wishing Sheeran a happy birthday:
News of his death was quickly followed by tributes on social media from people in the music industry and beyond - including British MPs, Chelsea Football Club and celebrity chef Jamie Oliver.
It all started with a YouTube channel
Edwards' success story began when he was 15, when his mother gave him a video camera for Christmas.
He began filming around the west London council estate he lived in, uploading videos of his friends singing and rapping to YouTube.
"It was a frustration of going to school and everyone talking about: 'How do we get our videos on MTV?," he told the BBC in 2014.
"YouTube was like a year old. I was like, 'I've got a camera for Christmas, I'm going to start filming people and uploading it'.
"Everyone was looking at me like, 'What are you doing, like you can compete with these major corporations' but I think I was early enough to believe that I could make a change."
He kept filming content for SBTV, named after his rapping name SmokeyBarz, while studying creative media at Ealing Green College.
His channel built up a loyal following and, after several attempts at negotiating with Google, began earning a share of the advertising revenue from YouTube.
Edwards was eventually able to quit his day job at clothing chain Topman and launch SBTV as a production company.
In 2014, he was awarded a Most Excellent Order of the British Empire, becoming one of the youngest people to receive the honour.
SBTV is credited with launching the careers of countless artists including Ed Sheeran, Jessie J, Skepta, Rita Ora and Stormzy, by featuring them on his channel when they were starting out.
"We've lost a legend today," YouTube wrote in a statement on Twitter.
"Jamal Edwards was an inspiration to so many, supporting artists and shaping culture through SBTV."