Sejersted, a historian, headed the five-member Norwegian Nobel Committee from 1991 to 1999 when it bestowed the prestigious honour on some of the world's most iconic pacifists, including Myanmar opposition leader Aung San Suu Kyi in 1991 and Mandela and de Klerk in 1993.
He died overnight between Monday and Tuesday, his family told Norwegian news agency NTB.
One of the more controversial decisions made by the committee during his tenure was to give the 1994 prize to Palestinian leader Yasser Arafat, jointly with Israel's then president Yitzhak Rabin and foreign minister Shimon Peres.
Infuriated by the panel's decision to honour the head of the Palestinian Liberation Organisation, one of the five members quit the committee, in a rare move.
Before heading the committee, Sejersted had been a committee member since 1982.
Highly respected in Norway, he was the author of several economic history books and had served as the head of the Fritt Ord foundation for freedom of expression.