The star was found dead at his home in Essex this morning and police have remained at the property.
The death isn't being treated as suspicious and an Essex Police spokesman told The Sun: "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."
An East of England Ambulance spokeswoman added: "We were called at 8.08am with reports of a man who was unconscious in Brook Hill, Dunmow.
"We sent an ambulance officer, Essex and Herts Air Ambulance and one ambulance. Sadly a man in his forties died at the scene."
NO!! No. I'm absolutely devastated. Keith Flint. This is the worst news.
I'm so glad I got to see you one last time. My thoughts go to your family & of course to @the_prodigy :disappointed_relieved: #RIPKeithFlint pic.twitter.com/gOkl7yPvj1
- Bianca Westwood (@beewestwood) March 4, 2019
Live fast, die young. RIP Keith Flint, you twisted instigator.:clap::clap::clap: pic.twitter.com/SaQp9aHwr6
- Michael Rossell (@DroogJanus) March 4, 2019
Saw him twice a few months back live, can't believe I won't see him again... what a frontman he was! #keithflint pic.twitter.com/hOERNudVuV
- Instruct (@instruct) March 4, 2019
Keith performed vocals on The Prodigy's number one singles 'Firestarter' and 'Breathe' which were released in 1996.
After emerging in the early 90s, The Prodigy quickly became one of the UK's biggest bands and were known as the 'Godfathers of the Rave'.
According to The Sun, Flint moved to Braintree, Essex, as a child where he went on to meet Liam Howlett - co-founder of The Prodigy.
Gutted at the news about Keith Flint, who played a huge part in our team in the TTC days.
Thanks for everything, fella :cry: pic.twitter.com/0loDf9rYgE
- McAMS Yamaha (@McAMSYamaha) March 4, 2019
In recent years he had success as a motorcycle racing team owner and manager. His team won three Isle of Man TT races in 2015 and competed in the British Supersport Championship.
In a post to the band's official Instagram account, The Prodigy's Liam Howlett said Flint had 'taken his own life.'