OTM Holdings, LLC, announced Wednesday it had purchased the complex.
The company plans to redevelop the site into a wood fiber-based complex with multiple tenants.
As a player in the wood-fiber market, the complex will focus on turning fiber and wood waste into products like fuel and other engineered wood products.
Former owners of the site say they're happy to see it being used for something instead of being demolished.
A portion of the building is currently home to UMaine's Forest Bioproducts Research Institute.
The mill closed in 2015.