The sole accused in the Sadia Sukhraj murder Sibonelo Mkhize was found guilty of all charges in the KwaZulu-Natal High Court in Durban on Monday.
Judge Esther Steyn found that Mkhize and his accomplice Siyabonga Bulose were "reckless of the consequences that would ensue" as a result of their actions.
"It is significant that the accused and Bulose decided to be armed at the time of the robbery. It speaks to the fact that you foresaw retaliation and decided to have the upper hand in shooting any opposition they might encounter."
She said that he robbed Sadia's father Shailendra Sukhraj and his family at gunpoint "and should accordingly be held accountable for the murders that followed the incident."
The judgment was delivered more than a year after the crime was committed in Shallcross, Chatsworth on May 28, 2018.
Mkhize killed Sukhraj during a botched hijacking. He pleaded not guilty to murder and robbery with aggravating circumstances.
Mkhize's accomplice, Siyabonga Bulose, was killed while fleeing from the scene.
On the day of the incident, the two demanded car keys from Sadia's father, well-known Pastor Shailendra Sukhraj, at gunpoint.
Sukhraj threw the keys at them and while both were fleeing the scene with Sadia inside the vehicle, Shalendra pulled out his licensed firearm and fired several gunshots towards the driver.
The Grade 4 pupil at Everest Primary was shot in her abdomen and was taken to Chatsmed Hospital where she later succumbed to her injuries.
The cause of death was a gunshot wound to the chest. Bulose died immediately after the car came to a stop. His cause of death was described as a penetrating gunshot wound to the pelvis.
Sadia's death sparked massive public outcry over crime in Chatsworth.
An off-duty police officer arrested Mkhize a short distance from Sadia's grandparents' home.