Kim Yong Nam, president of the Presidium of the North's Supreme People's Assembly (parliament), sent a message of sympathy to South Africa's president Jacob Zuma, according to the official Korean Central News Agency (KCNA).
Kim expressed "profound condolences" to the South African people and Mandela's family, it said.
The message marked North Korea's first official reaction to the death of the anti-apartheid leader.
Kim said in his message that "the feats performed by Nelson Mandela in the struggle against racism and for democracy in South Africa would always be remembered by the South African people and progressive mankind," the agency reported.