It is thought the development would support 2,000 jobs in the area.
It would include apartments, retail and sports facilities and a 50-acre business park in the 330-acre site.
Greencore has submitted plans to Carlow and Laois County Councils for rezoning of the former Irish Sugar plant on the edge of Carlow town.
The company is using the Dublin Docklands and the Digital Hub as its inspiration for the project, called The Carlow Gateway Commercial Centre.
Greencore's Development Director Geoff Doherty said the plan, if adopted, would transform a large area of Carlow town, and part of the plan includes a 35-acre walkway along the River Barrow.
But unions are unhappy with Greencore's plans.
SIPTU's National Industrial Secretary, Gerry McCormack, accused Greencore of spending the money it got from the EU for exiting the Irish sugar business on development, rather than on its former employees and beet farmers.
On RTÉ Radio's Morning Ireland, he said workers were facing Christmas without having been given their redundancy payments under the terms recommended by the Labour Court.
