The 145-acre site contains several buildings and will be redeveloped in two phases.
WEDC is contributing to the first phase, which focuses on a 70-acre parcel on the south side of the site which was bought by Ariens Company in October.
Ariens has already begun to renovate a building there into a research and development facility.
"This building has been basically a warehouse for the foundry," said Dan Ariens, Chairman and CEO. He added,"We gutted it, polished the floor, painted it white, you can see the ceilings, the walls are all white, put in brand new lighting so all that lighting gives us a real bright brand new manufacturing plant."
As a part of the deal, the city will build a new road and bridge crossing.
"We're very optimistic about the future of this site, and we expect the project will add tax base and also act as a catalyst to receive even more development in the area," WEDC CEO Mark Hogan said.
"We could not do this alone," Brillion Mayor Gary Deiter said. "We would be in debt for many, many years, because I don't think the city could take on the responsibility of tearing these buildings down and making a viable property for our future."
Work is underway and is expected to be completed in late 2020.
Ariens says it already has 40 workers in its research and development facility, formerly known as Plant 3. Ariens says it could eventually add up to 70.
Brillion Iron Works closed in September 2016, and 350 people lost their jobs.