The party was attended by African National Congress President Jacob Zuma, who said Mandela's legacy is one of defense of democracy and leadership by the will of the people, the South African Web site News24.com reported.
"We are celebrating the life of man who became a symbol and embodiment of hope for African people in particular, and the ANC in general -- a symbol of sacrifice, unity and of liberation," Zuma said in the village of Qunu, where Mandela was feted.
On Friday, his actual 90th birthday, Mandela gave interviews to Western news outlets, his first in four years, and said that while he was happy to have reached 90, his thoughts were still with Africa's poor and oppressed masses.
"Poverty still grips our people," he told CNN. "If you're poor, you're not likely to live for long."
A soccer festival and 500 politicians and anti-apartheid veterans were expected at Saturday's celebration, the network said.