Transport Canada has widened highway 69 into a four-lane road between Highway 637 and Estaire, near Sudbury, to ease traffic congestion, reduce travel time and increase user safety.
The transport department widened the 13km road at a cost of C$68.2 ($68.1m), which was jointly funded by the federal and state governments of Canada and Ontario.
The federal government, through its Building Canada Fund, contributed C$35.8m ($35.7m), while the remaining amount was supplied by the state through the Northern Highways Program.
Canada Foreign Affairs Minister John Baird said: "As a gateway to Northern Ontario, Highway 69 is an important link in the Trans-Canada Highway, and these improvements will increase safety for local commuters and tourists, while enhancing economic growth in the region."
Canada Northern Development and Mines Minister and Sudbury Parliament Provincial Member, Rick Bartolucci said: "An expanded, modern Highway 69 will provide residents with a safer, more efficient drive and promote economic development in the North."
The scope of the project included construction of an underpass at Highway 637 and an overhead wildlife crossing bridge.
The upgrade project has also brought a section of the highway into operation that bypasses a series of dangerous curves.
The new corridor is also expected to help grow the local tourism and recreation sectors, as well as improve the economy of the region.