In a televised address to the nation late on Wednesday, the 75-year-old said he was a disciplined member of the ANC, to which he had dedicated his life.
“I fear no motion of no confidence or impeachment … I will continue to serve the people of South Africa and the ANC. I will dedicate my life to continuing to work for the execution of the policies of our organisation,” Zuma said.
“No life should be lost in my name. The ANC should never been divided in my name. I have therefore come to the decision to resign as president of the republic with immediate effect.”
The resignation ended an extraordinary day in South African politics, which had begun with a dawn raid on a business family at the centre of the recent corruption allegations levelled at Zuma.
At noon, ANC officials announced they would vote for an opposition party’s no-confidence motion in parliament on Thursday.
Late in the afternoon, Zuma gave an angry and rambling TV interview to justify his refusal to obey his own party’s order to step down.
But his speech was more confident and warm. The president expressed his gratitude to the ANC and South Africans for the privilege of serving them at the “pinnacle” of public life.
Zuma’s resignation leaves the path clear for deputy president, Cyril Ramaphosa, who took over the leadership of the ANC in December, to be elected by parliament to the highest office.
Zuma, a former anti-apartheid activist who has led the ANC since 2007 and been South Africa’s president since 2009, was due to leave power next year.
His tenure has been marred by economic decline and multiple charges of graft that have undermined the image and legitimacy of the party that led South Africans to freedom in 1994.
The chaotic political crisis of recent days has further damaged the ANC, and angered many South Africans who are increasingly impatient with the party’s opaque internal procedures.
Ramaphosa won a bitterly fought internal election in December and is seen as the standard bearer of the party’s reformist wing. Party strategists wanted Zuma to be sidelined as quickly as possible to allow the ANC to regroup before campaigning starts for elections in 2019.
The party suffered significant setbacks at municipal polls in 2016 and could be forced into a coalition government at the national level, experts say.
As president, Ramaphosa will have to balance the need to reassure foreign investors and local businesses against the intense popular demand for dramatic measures to address South Africa’s deep problems.
The 65-year-old former trade union leader has said South Africa is coming out of a “period of uncertainty, a period of darkness, and getting into a new phase”.
Richard Calland, an expert in South African politics at the University of Cape Town, said the departure of Zuma from office would give Ramaphosa “the chance to rebuild government and the party at the same time”.
In recent days, the rand has strengthened and many analysts have revised upwards their predictions of South Africa’s economic growth.