This election featured voters with no memory of the white-minority rule that ended in 1994.
The African National Congress (ANC), the liberation movement that swept to power two decades ago under the leadership of Nelson Mandela, had 57.6 per cent of the vote with just over a quarter of ballots counted, the electoral commission said.
Its nearest rival, the Democratic Alliance, held 29.2 per cent, backing predictions the party, which is gradually shedding its image as the political home of white privilege, would improve on the 16.7 per cent it won five years ago.
Election officials said turnout was extremely high and that voting in the fifth election since the end of apartheid had gone smoothly, with only a handful of incidents at the 22,000 polling stations nationwide.
(READ MORE: The ANC put redress at the forefront of their policies: Sisulu)
Pre-election polls had put ANC support near 65 per cent, only a shade lower than the 65.9 per cent it won in the 2009 election that brought President Jacob Zuma to power.
The ANC's enduring popularity has surprised analysts who had said its support could ebb as the glory of its past recedes into history and voters focus on the sluggish economic growth and slew of scandals that have typified Zuma's first term.
(READ MORE: S.Africa’s political & business future is beyond elections)
Africa's most sophisticated economy has struggled to recover from a 2009 recession - its first since 1994 - and the ANC's efforts to stimulate growth and tackle 25 per cent unemployment have been hampered by powerful unions.
South Africa's top anti-graft agency accused Zuma this year of “benefiting unduly” from a 23 million dollar state-funded security upgrade to his private home at Nkandla in rural KwaZulu-Natal province that included a swimming pool and chicken run.
Zuma has denied any wrongdoing and defended the upgrades as necessary for the protection of a head of state. He confidently told reporters on Monday the Nkandla controversy was "not an issue with the voters".
His personal approval ratings have dipped this year, but Zuma appeared relaxed and assured as he voted at a school near Nkandla, ending what he called a "very challenging" campaign.
"I hope that all voters will cast their votes free," he told reporters. "This is our right that we fought for."