The group behind betting agency Ladbrokes is being investigated under anti-money laundering and counter-terrorism laws.
The enforcement investigation will determine if Entain Group is meeting its obligations under laws designed to stop the financing of serious and organised crime.
It will be run by the Australian Transaction Reports and Analysis Centre (AUSTRAC), the government's financial intelligence agency.
AUSTRAC chief executive Nicole Rose said corporate bookmakers shouldn't underestimate the importance of meeting their obligations.
"Reporting entities have a responsibility to ensure they identify, assess and manage risks of money laundering and terrorism financing, develop adequate processes and devote the necessary resources to comply with their ... obligations (under the act)," she said.
In a statement, AUSTRAC noted it had "a range of regulatory tools and enforcement powers available to it and will not hesitate to take action where suspected non-compliance is identified".
Its ongoing supervisory campaign of corporate bookmakers could lead to other areas of focus within the sector, although it did not add further comment due to the ongoing investigation.
Along with Ladbrokes, Entain owns Australian betting site Neds, European book bwin and American sports and casino betting operation BetMGM.
According to its 2021 annual report, Entain's net gaming revenue was $A6.6 billion.