The singer was found dead at his home in Essex. It is not known how he died but police are not treating his death as suspicious.
Essex Police said: ”We were called to concerns for the welfare of a man at an address in Brook Hill, North End, just after 8.10am on Monday.
”We attended and, sadly, a 49-year-old man was pronounced dead at the scene. His next of kin have been informed.
”The death is not being treated as suspicious and a file will be prepared for the coroner.”
Keith started off with the group – formed in 1990 by keyboard player and songwriter Liam Howlett – as a dancer, but gradually took centre stage as main vocalist on mid-90s hits such as Firestarter and Breathe.
His bandmates have said: “It is with deepest shock and sadness that we can confirm the death of our brother and best friend Keith Flint.”