Holly Raper, 27, from Chorley was left unable to talk or walk following the crash in December 2011 which happened on her gap year in Tasmania.
The quad bike had faulty rear brakes and a flat tyre and Holly was not given a helmet or training.
A Tasmanian court awarded the damages to pay for her round-the-clock care.
Holly, who was 21 at the time of the accident, was herding cattle for the first time when she fell off the vehicle.
She can now only communicate by blinking and needs two carers 24 hours a day. It is feared she will never walk again.
Her family were awarded £175,000 in 2013 for her injuries but then sought damages over health and safety breaches.
The £6.8m award will help with adapted accommodation, transport, care and ongoing therapy for Holly after her parents sued the farm owners, said her lawyers.
Peter Rigby, from Fletchers Solicitors, said: "This judgment allows them to get the professional support, treatment and equipment Holly needs and for her to have the best possible quality of life."
The money will be paid by insurers for the farm on King Island.
Holly's parents Chris and Elaine said in a statement: "We are relieved that the long legal process is at an end and that Holly will be able to continue to receive the support she needs now and into the future.
"With this matter now concluded, our energies can be solely directed on helping our daughter in her ongoing recovery."
A Lancashire woman who suffered severe brain damage during a quad bike accident on a farm in Australia has been awarded £6.8m compensation.