Walker, a passenger in the car driven by his friend and financial adviser Roger Rodas, died on Saturday when the 2005 Porsche Carrera GT smashed into a light pole and tree, and then exploded in flames.
The Los Angeles County coroner's office released the autopsy results on Wednesday. The report also says Rodas was killed by the impact.
Walker starred in all but one of the six Fast & Furious blockbuster films that glorified fast cars and dangerous driving.
Sheriff's investigators are still trying to determine exactly what caused Rodas to careen out of control.
They have said speed was a factor.