Joyce Banda was sworn in as Malawi's first female president in a ceremony in the capital Lilongwe on Saturday, two days after the death of her predecessor, Bingu wa Mutharika.
President Jacob Zuma has congratulated Banda for assuming the Presidency.
He also commended the Government and people of Malawi for upholding their country's constitution and ensuring a peaceful and orderly transition.
Banda, who will also be Southern Africa's first female Head of State, has declared an official 10 days of mourning for the late President Mutharika.