The Lane Cove Tunnel in north Sydney for $A630 million has been sold to The Transurban group.
The ABC reports the sale is yet to receive full approval from the New South Wales state government.
The acquisition means Transurban now owns the 3.6km tunnel, along with the adjacent M2 motorway.
Lane Cove Tunnel has been struggling to make its projected profits for some time.
It was reported in September last year that the owner, Connector Motorways was unable to meet debt repayments because traffic volumes had not met original forecasts of 100,000 cars per day.
Connector Motorways went into receivership in January. Investors have written off their interest in the company.
Lane Cove Tunnel motorway runs under Epping Road and links the M2 Motorway at North Ryde with the Gore Hill Freeway at Artarmon.
It opened in early 2007 and cost $A1 billion to build.