The 26-year-old from Kilham, near Bridlington, suffered fatal injuries after he was involved in an accident involving four bikes at the Southern 100 meeting.
A statement from the organisers said: “The Southern 100 MCRC, organisers of the Southern 100 International Road Races, regret to announce that following an incident involving four-competitors at Stadium Bends during the 600cc Challenge race, Driffield rider James Cowton succumbed to his injuries.
“The other riders involved, Ivan Lintin is in a critical condition, whilst Jamie Coward has shoulder injuries and Mickey Evans leg and arm injuries.
“Southern 100 Racing extends it sincere condolences to family, relatives and friends of James Cowton at this very sad time.
“The organisers are carrying out a full investigation in conjunction with Isle of Man Constabulary into the circumstances of the incident on behalf of the Coroner of Inquests.”
At last year’s Southern 100 meeting, Cowton had set a new track record for the 650 class and claimed three second places, one third, one fourth, two fifths and a sixth placed finishes.
He had won the Bridlington Free Press Sports Person of the Year award in 2014.