"There is a need for very strong signals to be sent to all rapists that sexual violence is absolutely unacceptable and that they will have to face the consequences of their terrible acts," Pillay said.
"The entrenched culture of sexual violence which prevails in South Africa must end."
She was reacting to the rape and mutilation of 17-year-old Anene Booysen, who was found disembowelled at a construction site in South Africa at the weekend and later died in hospital.
It is suspected she was gang-raped, but police said Thursday they were still investigating.
The case has shocked South Africa, which has one of the world's highest rates of reported rape.
Few cases reported
While welcoming strong reactions from President Jacob Zuma and others, Pillay said: "It should not have taken this particularly atrocious case … to underline the urgent need for a more thorough response across the whole spectrum of South African society to tackle the root causes of this pandemic of sexual violence."
"The fact that tens of thousands of rapes continue to take place every year in South Africa is a clear indication that the problem must be addressed in a much more robust manner," the high commissioner for human rights said.
Official statistics show that around 65 000 sexual offences were committed in South Africa last year alone.
But police estimate that only one in 36 rape cases gets reported, and recent studies have found that more than one quarter of South African men admit to raping a woman or girl.
Pillay expressed outrage that arrest and conviction rates of rapists "remain extremely low" in South Africa.
"This is not only a shocking denial of justice for the thousands of victims, but also a factor that has contributed to the normalisation of rape and violence against women in South African society," she said. – AFP