Maarohanye also hurt two other kids when he drove into a crowd in 2010, while high on cocaine and morphine and racing.
The BBC said Maarohanye was convicted of murder, attempted murder, racing on a public road and driving under the influence of drugs.
Themba Tshabalala, the motorist with whom he was racing, was convicted of the same crimes, the broadcaster said.
They are to be sentenced Nov. 30.
Notable deaths of 2014 [PHOTOS]