"With deep sorrow and a profound sense of loss, the African National Congress received the sad news" of the death of Mandela, Xinhua cited from a party statement.
Just before midnight Thursday, President Jacob Zuma announced that Mandela, 95, had died at his home in Houghton, Johannesburg.
"Our nation has lost a colossus, an epitome of humility, equality, justice, peace and the hope of millions, here and abroad," the statement said.
Nelson Mandela, born in the village of Qunu, Eastern Cape Province, joined the African National Congress in 1942.
In his lifetime of struggle through the ANC, he assumed and was assigned various leadership positions.
"His life gives us the courage to push forward for development and progress towards ending hunger and poverty. As we said of him while still alive, and we say so now," the ANC said.
"We have you, Madiba (Mandela), as our nearest and brightest star to guide us on our way. We will not get lost," the party said.
"To the entire family of Mandela, we extend our heartfelt condolences. He was as much yours as he was ours, probably his dedication to the ANC family robbed you of a father. We will, from this minute on, as always, walk this journey with you to the end," said the ANC.