Anita Board was on a solo “test run” when her vehicle hit a concrete barrier at the Perth Motorplex, police said.
Paramedics treated her at the scene on Saturday before taking her to hospital, where she died a day later.
The girl had been attempting to gain her licence for junior dragster racing, the Australia National Drag Racing Association (Andra) said.
She had just turned eight – the minimum age required to race under official rules – and was driving a 210cc dragster, local media reported.
The girl’s father, Ian Board, posted a message online saying “my heart [is] in a million pieces”.
“We will need … the love and support in the days weeks months ahead,” he wrote in local community forum.
Members of the drag racing community have posted tributes online, including under the hashtag #HelmetsOutForAnita.
Andra said in a statement: “Anita was undergoing a licencing pass at the Perth Motorplex, as part of the process for her to receive her racing licence, when this tragic accident happened.
“Junior racers must adhere to stringent safety rules and regulations regarding safety equipment, and their dragsters must meet specific safety requirements. ANDRA regulations for junior competition are benchmarked against similar organisations internationally.”
Mike Sprlyan, of Junior Dragster Australia, told news outlet Perth Now that beginners aged between eight and 17 reached top speeds of about 40-50km/h (25-30mph).
Police said they would prepare a report for a coroner.
This story was originally published in BBC