Zuma was ordered to report back to prison and arrived at 6:00 am (0400 GMT) at a detention facility in eastern town of Estcourt where was “admitted into the system”, the prison service said.
But he was let go in just over an hour as part of a “remission process” aiming to address overcrowding in prison, according to Correctional Services national commissioner Makgothi Thobakgale.
“Upon admission into the system he was subjected to administrative processes… He was then released,” Thobakgale told a press conference in Pretoria.
Zuma was sentenced to 15 months in June 2021 after refusing to testify before a panel probing financial corruption and cronyism under his presidency — but was freed on medical parole just two months into his term.
He started serving his term early in July 2021.
His jailing sparked protests that descended into riots and looting that left more than 350 dead in the worst violence to hit the country since the advent of democracy in South Africa.
The following month, he was admitted to hospital for an undisclosed condition before being granted medical parole.
In November last year an appeals court found the release was illegally granted and ordered Zuma back to the Estcourt Correctional Centre in the eastern KwaZulu-Natal province.
South Africa’s prison service, which had granted Zuma’s conditional release, appealed the decision, but the bid was dismissed by the Constitutional Court last month.
Thobakgale said the ex-president was ordered to return to jail on Friday in compliance with the ruling.
But Zuma immediately benefited from a remission of non-violent offenders approved by President Cyril Ramaphosa, Justice Minister Ronald Lamola said.
More than 24,000 inmates, about two-thirds of them under correctional supervision and parole, are to be released under the process, said Lamola.
The move “will alleviate overcrowding” which “poses a direct threat to inmate health, security, and management, and it could lead to a surge in gangsterism,” the minister said.
Mzwanele Manyi, a spokesman for Zuma’s foundation said the ex-president was “at home” and consulting with his legal team.
Zuma served as president from 2009 to 2018 before being forced out over graft allegations.
Besides his 2021 contempt of court conviction he is facing separate charges of corruption in an arms procurement scandal dating to the late 1990s, when he was vice president.