Zuma will tie the knot at his family homestead in Nkandla in KwaZulu-Natal province, said presidential spokesman Mac Maharaj.
"I can confirm that President Zuma will formalise his relationship with his fiancee, Ms Bongi Ngema, in a private traditional ceremony at Nkandla this weekend," Maharaj said.
Zuma, a known polygamist, will be married the sixth time. He divorced Nkosazana Dlamini-Zuma, South Africa's candidate for the African Union top post, in 1998. Another wife, Kate, committed suicide in 2000.
"The president currently has three wives. This will be his fourth wife," Maharaj said.
The president, who turned 70 last Thursday, is believed to have fathered around 20 children.
Ngema, who accompanied Zuma on a state visit to the G20 summit in South Korea last year, has a three-year-old son with him. She has a business degree among other academic qualifications.
But Zuma himself will foot the bill for wedding, the presidency said in a statement released Sunday afternoon.
"There is no government involvement or cost," Maharaj said in a statement.
He further clarified that the government did not pay for the maintenance of the president's spouses, because the position of "First Lady" does not formally exist in the country.
The state did pay for logistical support when spouses had to accompany the president on official business. Children who were studying full-time and financially dependent up to the age of 27 had 60 single domestic flights a year "to reunite with their parents," Maharaj said.
Zuma's adventures with women have often sparked controversy. In 2006 he was acquitted of rape charges after having consensual sex with an HIV-positive activist and family friend. He famously told the court he had taken a shower to protect himself against infection.
In 2009 he fathered a child with the daughter of 2010 World Cup local chief Irvin Khoza on the eve of the global event.
Asked at his birthday party Friday whether he was done with marriage, Zuma replied, "I think so."