The 20-year-old hit back hard when the unknown assailant punched her for not handing over a cigarette, forcing him to flee.
"When she said no, he got upset and lashed out at her – and she lashed right back," a police spokeswoman told AFP.
"She punched him three times in the face with a karate punch and kicked him with a karate kick. She did pretty well – not that we're encouraging that sort of thing."
The woman, who has been practising karate for 10 years, was not available for comment after Saturday's incident in the centre of Alice Springs, gateway town to Uluru or Ayers Rock.