Victims reacted angrily to the judge's decision in the Pretoria High Court to extend bail pending an appeal hearing on 19 June.
The former Grand Slam champion will now be placed under house arrest.
Hewitt, 75, was found guilty of raping and sexually assaulting girls he coached in the 1980s and 1990s.
Judge Bert Bam criticised the Australian-born player at his sentencing on Monday for not showing remorse during his trial.
He said justice must be seen to be done, even for ageing offenders.
One of the victims who gave evidence at the trial said that Hewitt had assaulted her when she was just 12 years old.
The judge said at the time of Hewitt's conviction that the striking similarities between the three victims' testimonies showed that his conduct was calculated.
Speaking at the sentencing hearing in Pretoria, Hewitt's wife Delaille had begged the court to show mercy and not award a custodial sentence.
Hewitt had testified that he suffered from poor health.
The BBC's Nomsa Maseko, in Johannesburg, says the tennis champion has also been ordered to pay a fine to the South African Department of Justice, which will help fund its campaigns against sexual abuse.
Hewitt's lawyers say they will appeal against his conviction and sentence.
He was suspended from the International Tennis Hall of Fame in 2012 over the allegations of sexual abuse.
Hewitt played initially for Australia, later moving to South Africa and taking citizenship there.
He was a member of the South African team which won the Davis Cup by default in 1974.
India, their opponents, refused to travel to South Africa for the final as a protest over the government's apartheid policies.
Former tennis star Bob Hewitt has been granted bail by a South African court, after receiving a six-year prison sentence for raping underage girls.