The Australian Financial Review revealed last week the Mint, owned by the Western Australian government, was buying up to A$200 million of conflict gold a year from a convicted killer in Papua New Guinea.
Walsh said the Mint took environmental, social and governance reporting seriously.
"I have initiated an independent third-party review of the Perth Mint's audit processes," he said.
"The review will also assess the arrangements with licensed counterparties that may deal with artisanal small-scale mining (ASM)."
The Mint has suspended relationships with all companies and aggregators dealing with ASM while the review is undertaken.
The London Bullion Market Association has initiated a review of the Mint's responsible sourcing processes and practices.
Perth Mint CEO Richard Hayes said the LBMA conducted an independent audit of the Mint's sourcing practices each year.
"We are vigilant in our assessments of companies from which we source gold and other metals for processing and are confident we fully comply with regulatory requirements and the responsible gold guidelines set out by the global gold industry's governing bodies," he said.
"In addition to our own strict audit protocols, we also use the Heidelberg Institute's Conflict Barometer, a publication which monitors and tracks events and trends in global conflict developments and settlements across multiple countries to inform our assessments."