With results still to come in, the party has scored its biggest electoral victory in 10 years of power in post-apartheid South Africa.
President Thabo Mbeki's party clinched a two-thirds majority in the elections, surpassing its strong showing of 66% in 1999 and 64% in 1994, when Nelson Mandela led the party to victory in the country's first democratic polls.
After 61.2% of the total number of registered votes were counted, the ANC was miles ahead of its rivals at 69.6% the Independent Electoral Commission announced on Friday.
However, the commission added, turnout appeared to be around 75% the estimated 21 million registered voters - a figure far lower than those of the previous two democratic elections.
Trailing far behind in second place was the white-based Democratic Alliance with 13% of Wednesday's vote - also a gain from its showing in the previous elections.
In third place, the Zulu nationalist Inkatha Freedom Party (IFP) won 5.8% of the vote although its fate hinged on the outcome of the race in its stronghold of KwaZulu-Natal province, the Zulu heartland in the country's eastern coast.
The United Democratic Movement, led by former ANC heavyweight Bantu Holomisa, got 2.9%.
The New National Party, the heir to the National Party which led apartheid South Africa for 50 years, was seen as the big loser in the elections, garnering just 1.9% of the vote, the independent electoral commission said.
The NNP won 20% in the 1994 elections but has been on a steady decline since.