The two-horse race between presidential hopefuls Nkosazana Dlamini-Zuma and Cyril Ramaphosa heated up as voting by ANC conference delegates finished mid-morning and counting started.
The party's treasurer-general Zweli Mkhize and Naledi Pandor declined to stand for the position of deputy president, leaving it a shoot-out between Mpumalanga's ANC chairperson David Mabuza and NEC member Lindiwe Sisulu.
Following the announcement there were jubilant scene in the hall as Ramaphosa hugged supporters.
A veteran in the battle to help end apartheid, which saw the country ruled by the white minority, Ramaphosa is now one of the country's most successful businessmen and has been duly supported by the business community. Ms. Dlamini-Zuma had promised the radical economic transformation her ex-husband never delivered.
The rand extended gains to climb 4 percent to 12.5938 per dollar by 7.15 p.m.in Johannesburg, the biggest jump in two years to the strongest level since March.
The ANC's reputation has taking a beating during Zuma's scandal-ridden tenure, causing rifts that threaten to split Africa's oldest liberation party.
He has pledged to introduce a minimum wage for workers and will consider privatising some of South Africa's state-owned conglomerates.
Voters may see the transfer of power as a break with the Zuma era, and it should boost the ANC's chances or retaining an overall majority in the 2019 elections.
He turned his connections as a former union leader into business ventures that at times have proven controversial.
The vote was a long and acrimonious process.
Mr Ramaphosa will have to take tough decisions to restore investor confidence and will confront a number of obstacles that will make it hard to resuscitate the economy, according to Ben Payton, head of Africa Research at Verisk Maplecroft, a Bath, England-based risk-advisory company.
A victor had been expected to be announced on Sunday, but owing to long delays, the vote had been pushed back repeatedly. "Before today we said Dlamini-Zuma could emerge as a victor".