The deal is valued at $4.9bn with Vale receiving $1.1bn in cash and a 22% stake in Norsk. The Norwegian firm said the deal would improve competitiveness by securing access to bauxite and alumina.
About 3,600 Vale employees will be transferred to Norsk, which already employs 19,000 people in 40 countries. Vale is one of the world's largest iron ore mining company's.
As part of the deal, Norsk will buy Vale's 60% stake in the world's third-biggest bauxite mine, Paragominas, Brazil.