0729 GMT January 23, 2020
Zuma testified at the inquiry in Johannesburg into the so-called "state capture" scandal after previous witnesses gave damning evidence against him, AFP reported.
He is accused of overseeing mass looting of state assets during his nine-year tenure before being ousted by the ruling ANC party in 2018 and replaced by his deputy, Cyril Ramaphosa.
In his much-anticipated appearance, Zuma seemed relaxed as he spoke uninterrupted for more than two hours.
"I have been vilified, alleged to be the king of corrupt people," he said. "I have been given every other name and I have never responded."
Zuma, who is set to face cross-examination during his appearance which may last all week, said he had been the victim of "character assassination over 20 years."
"This commission, according to those who are implementing things, must be the grave of Zuma, he must be buried here," Zuma said.
"There has been a drive to remove me from the scene, (they) wish that I would disappear... there is this conspiracy against me."
Zuma, 77, was not legally required to attend the inquiry, but it invited him to appear after other witnesses testified against him.
Led by Judge Raymond Zondo, the probe is investigating a web of deals involving government officials, the wealthy Gupta family and state-owned companies.
"I never did any... breaking the law with this family – never," he said.
Dismissing the term "state capture", he asked "you are saying to the international community that South African judges are captured, all political parties in government are captured, the executive is captured by this family?
"It's an exaggeration, it is meant to enhance this narrative against Zuma."
According to Angelo Agrizzi, one of the inquiry's previous witnesses, Zuma allegedly accepted a monthly $2,200 bribe (1,951-euro) delivered in luxury bags from a contracting firm that was trying to evade police investigation.
The money was in theory for his charity foundation.
Former finance minister Nhlanhla Nene, who was sacked by Zuma in 2015, testified that Zuma pushed policies on nuclear power and aviation designed to benefit the Gupta family.
The Gupta brothers are accused of fraudulently profiting from government contracts including energy and transport deals under Zuma.
Former deputy finance minister Mcebisi Jonas told the inquiry that the Guptas offered him the finance minister's job and even threatened to kill him after he refused to accept a $40 million bribe.
Sitting in central Johannesburg, the inquiry has heard from scores of witnesses over 130 days in session since last year.
Zuma has separately been charged with 16 counts of graft linked to an arms deal from before he became president.