A statement from the prime minister’s office said Mr Ruddock would conduct a "timely expert stocktake" that would determine whether there was any need to change the law to enshrine religious freedoms.
The announcement comes amid pressure from Coalition conservatives who want to see religious exemptions built into the bill to legalise same-sex marriage.
Mr Ruddock is due to report back by March 31 next year, throwing the broader debate on religious protections beyond the government's self-imposed Christmas deadline to legalise same-sex marriage.
But Treasurer Scott Morrison welcomed the review but said it "[did] not replace" the need to build religious exemptions into Senator Dean Smith's bill to change the Marriage Act.
"Any reforms to protect religious freedom at large should be undertaken carefully. There is a high risk of unintended consequences when Parliament attempts to legislate protections for basic rights and freedoms, such as freedom of religion," Mr Turnbull said in the statement.
