Mido Macia, 27, died of head injuries and internal bleeding after his arrest in Daveyton, east of Johannesburg.
An investigation was launched after video footage emerged showing the man being hauled through the streets with his hands cuffed to a police van.
President Jacob Zuma called the incident “horrific” and “unacceptable”.
Police Commissioner Riah Phiyega thanked people for revealing “callous and unacceptable behaviour”.
The eight officers were charged with murder on Friday – three days after the fatal incident.
Mr Macia, a taxi driver, was reportedly detained for parking his vehicle in a way that blocked traffic.
The video, apparently recorded by a bystander on a mobile phone, shows a large crowd watching as uniformed policemen tied him to the van, dragging him as they drove away.
Public anger grew after the footage was broadcast on television.
South Africa’s police watchdog – the Independent Police Investigative Directorate (IPID) – is examining the video as part of its investigation.
The South African Police Service expressed “extreme shock and outrage” at the mobile phone footage.
“From the video which has gone viral, it is obvious that the rights of Mido Macia were violated in the most extreme form,” it said in a statement,
“The behaviour displayed in that video, when it is committed by police who are expected to serve and protect, is to be abhorred,” it added.
The police force was already under intense scrutiny after officers shot dead 34 striking miners last August.
Its credibility was also dented when it emerged that the lead detective in the murder case against athlete Oscar Pistorius was himself accused of attempted murder.
The police service said it would give its full support to the IPID as it looked into Mr Macia’s death.