The 24-year-old Victorian rider and her horse Zidane received a 74.1 per cent score at the Sydney dressage qualifying event on Thursday, enough to earn a spot at the Games.
It marked three years to the day since Booth was injured in a car accident that left her a paraplegic.
Booth returned to the saddle just six months after the head-on road collision, and has competed at an international level twice since.
"I'm really pleased with how Zidane performed today, he is an absolute star who tries his heart out."
"Riding him is my therapy. It keeps me sane and when I'm on board it gives me freedom - he is my legs."
Booth's scores all but cement her place in the Australian Paralympic dressage squad, which will be announced next month.
"We're still waiting for the official team announcement in May but I'm starting to get excited that the Rio dream could come true," she said.
Paralympic Equestrian 101
Here's all you need to know about equestrian. At the Rio Paralympics, 78 athletes with their horses will fight for 11 gold medals. Men and women compete together.