Dayne Brajkovich, a former Hells Angels bikie who has served time in prison for drug offences, purchased $27,000 in gold from the mint in June last year, the ABC's Four Corners program reports.
The mint is required to conduct extensive checks on higher-risk customers but Mr Brajkovich told the program he was only asked for his driver's licence.
There is no suggestion Mr Brajkovich's money was sourced from illegal activity.
Perth Mint remains under investigation by financial crime regulator AUSTRAC, which last year ordered the appointment of an external auditor to the West Australian government-owned corporation after identifying compliance concerns.
The auditor is examining whether Gold Corporation, trading as Perth Mint, has complied with anti-money laundering and counter-terrorism financing obligations.
It is also investigating the mint's compliance with requirements relating to the reporting of suspicious matters.
Any confirmed breach of money laundering laws could leave the mint facing heavy criminal fines which would ultimately be paid by WA taxpayers.
A Perth Mint spokeswoman said the corporation "is required to and fulfils its obligation" to report to AUSTRAC if staff suspect a person or transaction is linked to a crime.
She said the mint had launched anti-money laundering and counter-terrorism financing remediation programs and processes to improve its engagement with customers.
"The Perth Mint acknowledges there have been instances of historical non-compliance that we are working through, including with regulators such as AUSTRAC, to rectify any shortcomings," she said.
Perth Mint is Australia's biggest gold refinery with a turnover of almost $22 billion last financial year.
It sold almost 20 million coins, medallions and bars to customers in more than 130 countries.
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