Zuma appointed Busisiwe Mkhwebane to replace Thuli Madonsela, whose non-renewable seven-year term expires this month.
Mkhwebane, 46, vowed that she would prioritise investigating issues surrounding the needs of the poor over state corruption, which has been at the forefront of Madonsela's time in office.
The outgoing ombudswoman found in a 2014 report that Zuma had "unduly benefited" from the refurbishment of his Nkandla rural home -- valued in 2014 at 216 million rand (then USD 24 million).
The Nkandla scandal has dogged Zuma's presidency, becoming a symbol of alleged corruption and greed within the ruling African National Congress (ANC) party and triggering several unsuccessful impeachment bids by the opposition.
More From This Section
Madonsela is currently looking into claims of what is described as "state capture" involving a politically-connected wealthy Indian migrant family, the Guptas.
She was due today to question Zuma over alleged misconduct including the accusations that he allowed the Gupta family to choose ministers.
But Mkhwebane, who starts work next week, said that while allegations of state corruption were important, her priority would be towards the poor.
"Which one is a matter of life and death. A person who is sitting without electricity, without hot water, children going to school without hot water, compared with the state capture," Mkhwebane said in an interview with the national broadcaster, the South African Broadcasting Cooperation.
Mkhwebane, a state security analyst with the country's intelligence agency, beat dozens of other candidates nominated by the public, and then interviewed by lawmakers.
All parties in parliament backed her nomination for the job, except the main opposition Democratic Party (DA), which questioned her credentials, calling her a spy because of her position as an immigration officer at South Africa's embassy in China.