Mthethwa, dressed in his usual smart suit, appeared expressionless as judgment was handed down.
During his trial, he exercised his right to remain silent and did not testify.
He also did not hand in a plea explanation.
A psychiatrist had told the court about how Mthethwa had no recollection of events that night, possibly due to alcohol consumption.
He was found not to have any mental illness, memory or personality disorders, aggression, paranoia or anti-social behaviour.
Kumalo is believed to have died from blunt force trauma. Mthethwa allegedly kicked and stomped her repeatedly.
The State alleged he was caught on CCTV camera as he parked his Porsche in Ravenscraig Road, Woodstock.
Judge Patricia Goliath said the CCTV acted as a “silent witness”.
The footage shows a dark car parking and a man getting out, before striding to the other side of the road.
Shortly afterwards, Kumalo is seen stumbling and falling down.
For 23 seconds, nothing is seen on screen. The footage then shows repetitive, forceful kicking to the middle of her body, as well as slaps and fist blows directed at her head off-screen.
Her fully clothed body lay next to the road for about an hour before it was discovered by a security guard.
The court accepted the footage as authentic evidence. This was after an attack by the defence on its admissibility, reliability and credibility.
Around 20 members of the Sex Workers Education & Advocacy Taskforce stood outside the court.
They held posters and sang Senzeni Na (What have we done?)
In attendance inside court was ANC NEC member Tony Yengeni, who also owned a fancy vehicle and faced impending court action.
Yengeni was arrested in Green Point in August 2013 after allegedly being spotted driving his white Maserati erratically.
Judgment in Yengeni’s drunken driving matter will be handed down on Friday.