"We feel very good... That he could leave hospital which indicates the progress he has made," Zuma told editors at a breakfast briefing in Pretoria.
"You have heard that Tata Madiba (Mandela's clan name) left hospital for his home...He remains critical but stable, responding to treatment," he said.
It is the first time that Zuma has commented on the status of former democracy hero since he was discharged from hospital at the weekend.
South Africa's first black President's hospitalisation had sparked worldwide concern during his stay for 86 days, including his birthday in July, in a Pretoria hospital.
"We acknowledge that he is old and that he is not well, but we are very happy that he has gone home."
Mandela has a long history of pulmonary illness and his advanced years may make recovery even more difficult, pulmonologists have warned.
The Presidency said on Sunday that Mandela was discharged from the Medi-Clinic Heart Hospital in Pretoria where he had been treated since his June 8 admission with a lung infection.