Tennis TV Grand Slams
The 75-year-old was found guilty in March of two counts of rape and one of sexual assault on girls he was coaching in the 1980s and 1990s.
Judge Bert Bam criticised the Australian-born player for not showing remorse during his trial.
He said justice must be seen to be done, even for ageing offenders.
Speaking earlier at the sentencing hearing, Hewitt’s wife Delaille had begged the court to show mercy and not award a custodial sentence.
But Judge Bam said the striking similarities among the three victims’ testimonies showed that Hewitt’s conduct was calculated.
According to the BBC, 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, who was a Grand Slam doubles champion in the 1960s and 1970s, is expected to appeal against his conviction and sentence.