Hinch, dubbed "The Human Headline" in Australia where he has worked as a print and radio journalist and television presenter, said he had been blackmailed by the woman who was a former business partner, the Herald Sun newspaper reported.
He is well known for his campaigning against sex offenders.
The alleged victim was interviewed for about 10 hours on Wednesday by detectives from the sex crimes squad.
It was believed she claimed Hinch assaulted her in a bed at his St Kilda Rd apartment in Melbourne about 12 months ago, the newspaper said.
Hinch, recently married for the fourth time, last night angrily denied all allegations.
The claims were "absolute rubbish," he said.
Hinch has enjoyed a controversial career. He has been sacked 14 times in his 45 years in journalism. He started his career in New Zealand newspapers.