The 33-year-old Briton was fatally injured in a fiery, 15-car pileup Sunday at the IZOD IndyCar World Championships.
The Clark County, Nev., coroner's office said Wheldon died of blunt force trauma to the head at University Medical Center in Las Vegas shortly after being transported there by helicopter following the spectacular accident, KLAS-TV, Las Vegas, reported.
The death was the first at the oval Las Vegas track since 1996 and the first IndyCar fatality since Paul Dana died during a practice run at Miami Homestead Speedway in 2006.
Also Monday, IndyCar drivers J.R. Hildebrand and Pippa Mann, injured in Sunday's multiple-vehicle mishap, were discharged from the same hospital.
Hildebrand, 23, who suffered a severely bruised sternum, and Mann, 28, whose burned little finger was surgically repaired, left UMC one day after the crash.
Mann's finger will require another operation within 2-3 weeks but she is expected to make a full recovery.
Will Power, whose bid for a series championship was cut short by the crash, was treated for lower back pains and released.
He was seeking to make up 18 points on leader Dario Franchitti in the IndyCar season finale but Franchitti instead went to claim his record third straight and fourth overall title.
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