More than 1.3 million tonnes of grain will be exported from Port Kembla each year once a new grain handling facility begins operations at the end of 2015.
The first shovel of soil was turned on the $75 million project on Tuesday.
It includes an upgrade to berth 103, new grain storage with a 100,000-tonne capacity, rail facilities and a mobile ship loader.
Up to 75 construction jobs will be created once work kicks off and 10-12 more jobs will be created when the facility is fully operational.
As well as the huge export capacity, the depot would also import 150,000 tonnes of other agricultural products annually, Quattro Ports chairman Tony Day said.
Quattro is a joint initiative between Qube Holdings, Emerald Grain, Cargill Australia and Noble Resources.
NSW Ports executive general manager commercial Dom Figliomeni said the project would create jobs throughout the region.
"The maintenance and ongoing work that goes with that, it's not only the direct full-time jobs, but the ones that flow through that as well."
He said NSW Ports, which leased the port for $760 million last year, was committed to the growth of the port.
Minister for Roads and Freight Duncan Gay congratulated NSW Ports and Quattro Ports on the development.
"It's a win-win, there's a new facility, money invested in the area, jobs in construction and operation and no noticeable increase in the road traffic."
The project should be complete by October 2015.