Cadet has died in a car crash on the way to a gig at Keele University in Staffordshire.
The rapper from south London, whose real name is Blaine Cameron Johnson, died in the early hours of Saturday morning.
The news of Cadet's death was confirmed by his family on his official Instagram account.
In a statement to Radio 1 Newsbeat, his management said the 28-year-old was a passenger in a taxi.
Cadet's cousin Krept - of rap duo Krept and Konan - led the tributes online, saying he was "heartbroken".
The 28-year-old had been rapping alongside Krept and Konan since he was a teenager.
His most recent single Advice, with Deno Driz, was released in October and peaked at number 27 in the charts.
Musicians, sports stars and DJs have all been paying tribute to the rapper.
Stormzy said he didn't know what to say, posting on Instagram that it feels "mad, weird" whilst Drake simply wrote RIP.
Cadet regularly appeared on BBC Radio 1Xtra and performed at MistaJam's Christmas Party last year.
Staffordshire Police confirmed Cadet died in the crash in Betley in the early hours of Saturday morning.
In a statement, the force said: "Blaine Cameron Johnson, 28, of London, died after the Toyota Prius he was travelling in was involved in a collision with a Vauxhall Combo van at 1.30am.
"He was pronounced dead at the scene."
A previous statement said that the drivers of both vehicles were taken to hospital with serious injuries and three others were also being treated in hospital.
Cadet was on his way to Keele University where he was due to perform at the student union night Fresh Friday.
It's billed as 'Staffordshire's Biggest Hip Hop, Garage and R&B Night'.
DJ Target posted on Twitter that Cadet was "a talent, and a lovely guy, always smiling, infectious energy."