She added that in determining the jail sentence for Zuma, the court found it impossible to conclude that he would comply with any other order.
"Mr Zuma has repeatedly reiterated that he would rather be imprisoned than to cooperate with the commission or comply with the order made," said Khampepe.
Zuma has previously expressed his unwillingness to appear before the commission, which has so far heard evidence directly implicating Zuma in wrongdoing.
In a previous 21-page letter written to Chief Justice Mogoeng Mogoeng, which the court has described as "scandalous", Zuma claimed that he was ready to be sent to prison.
In his letter, which he released to the public, Zuma claimed that the commission chairman, Zondo, was biased against him and that evidence presented against him was politically motivated.
Former Cabinet ministers, high-ranking government officials and executives of state-owned enterprises are among witnesses who have implicated Zuma in corruption.
Several have testified that while president Zuma allowed members of the controversial Gupta family to influence his appointment of Cabinet ministers and lucrative contracts at state-owned companies.
Zuma is also facing additional legal woes as he is standing trial to face charges related to bribes that he allegedly received during South Africa's 1999 arms procurement deal.
He has pleaded not guilty to the charges and his lawyers have applied for the lead prosecutor in his case to step down because of alleged bias against Zuma.