The 28-year-old was killed in his home country Kenya near Nandi a day after returning from the Continental Championships in Nigeria.
Bett made history in China after becoming the first Kenyan to win a gold medal in a short distance race on the world stage.
He is a also two-time African Championship medallist, whose twin brother is also a 400 metres hurdler.
His family and county police commander Patrick Wambani confirmed the tragic news.
How Nicholas Bett Died:
Nicholas Bett died in a road accident in Nandi County, Kenya.
Mr Bett died on the spot after the car he was driving hit a bump before losing control of his car at Sochoi near Lessos. The car veered off the road and landed in a ditch near Lessos along Eldoret-Kapsabet road on Wednesday morning.
Nandi Police Commander Patrick Wambani confirmed the death, saying preparations were being made to take Nicholas Bett’s body to a nearby mortuary.
Bett – who was part of Team Kenya that competed at the just-concluded African Athletics Championships in Asaba, Nigeria – was travelling back home from Nairobi.
May his soul rest in perfect peace.