Cathcart was driving a Citroen DS3 R3 in the top class of the British Rally Championship. He went off during the third stage of the Ulster Rally and was killed in the crash.
His co-driver Dai Roberts is injured, and still receiving treatment in the hospital.
"It is with deep regret that the Northern Ireland Motor Club can confirm that twenty-year-old Timothy Cathcart from Enniskillen, was sadly killed when his car left the road on the Fardross stage of the Ulster Rally," said a statement from the Northern Ireland Motor Club.
The rest of the event has been cancelled.
Auto123.com's thoughts and condolences are with Cathcart's family and friends and we wish Dai Roberts a speedy recovery.