Kjell Inge Roekke, a former fisherman who made his fortune in the oil industry, will begin by funding a research ship that will remove plastic from the ocean.
It will operate in partnership with the environmental organisation WWF.
He joins other billionaire philanthropists including Bill Gates, Warren Buffet and Mark Zuckerberg.
Mr Roekke has an estimated wealth of $2bn (Â£1.6bn).
"I want to give back to society the bulk of what I've earned," he said in an interview with the Aftenposten newspaper. "This ship is a part of that."
The research vessel will have a crew of 30, with space for up to 60 scientific staff and some laboratories.
It will remove from the water and melt up to five tons of plastic a day, the newspaper reported.
"Sea covers 70% of Earth's surface and much is not researched," Mr Roekke said.
He did not say how much the ship would cost or what else he would donate to. He and his wife already have a foundation for giving scholarships to postgraduate students.
Nina Jensen of the WWF said she was "far apart" from Mr Roekke's views on oil exploration and would "continue to challenge [him] when we disagree" but said she was excited about the ship project.
"I've never heard of a similar commitment," she said.
"The dream is to find a way of solving the great challenges of the sea, such as extreme plastic pollution."
A Norwegian billionaire has promised to give "the lion's share" of his money away.