The killing of Anene Booysen, who was mutilated and left to die in a small town in the Western Cape, echoed the gang rape of a student on a New Delhi bus last year, and has focused attention on South Africa's high rates of sex crime.
Hundreds of mourners, including politicians, packed a church in the town of Bredasdorp, while a tent was set up to accommodate those who couldn't fit inside.
Booysen was found by security guards lying a short distance from her house after partying at a bar last Friday evening. Her stomach was slit open down to her genitals and she died from her injuries in hospital.
She managed to identify one of her attackers before her death. Three men have been arrested and are due to appear in court on Tuesday. Booysen's brother told local media he knew one of the suspects.
"He was a friend of mine, we went to school together, stayed in one house, we were like brothers," Ryno Booysen said.
On Friday, hundreds of people marched through Bredasdorp, chanting "enough is enough"
President Jacob Zuma expressed shock and outrage, calling for the harshest possible sentences for the killers and a concerted campaign "to end this scourge in our society".
South Africa has the highest number of reported rapes per head of population of any Interpol member country, with more than 64,500 reported in 2011/2012.
Even when suspects are caught, only 12 percent of cases end in conviction and sex crimes seldom cause much public concern.
The Women's League of the ruling African National Congress is trying to mobilise the public into similar action to the protests against anti-female violence that took place in India after the New Delhi attack.
On Saturday, South African media reported police had arrested a Johannesburg pastor for luring a woman into his church and raping her.