Hadebe gestured angrily at Judge Nico Coetzee and repeatedly said "fuck you" before being led down to the cells under the court.
'The accused shows no remorse for what he's done'
Diepsloot residents expressed satisfaction with Hadebe's sentence while chanting and singing outside the court.
In September 2013 Hadebe raped and murdered five-year-old Anelisa Mkhonto. A month later he did the same to Yonelisa Mali, two, and her three-year-old cousin Zandile, in Diepsloot, north of Johannesburg.
He was sentenced to life imprisonment for raping and sodomising the toddlers and 15 years' jail for kidnapping them.
His name would be entered on the national sex offenders' register.
Hadebe lured the little girls from their Diepsloot homes and took them to his shack, where he raped them before suffocating or strangling them.
He left Anelisa's body at a nearby rubbish dumb, with a plastic bag tied over her head, and the bodies of the cousins in a public toilet.
Coetzee said Hadebe acted like an "animal", or possibly even worse, and the punishment had to fit the crime.
Hadebe testified in mitigation that he "was not well in the head" and became "insane" when he started drinking in 2005.
Coetzee said he was clearly not insane as he was obviously able to follow proceedings and make a meaningful contribution to the trial.
"The accused deprived these three children, who had a whole life to live before them, from the pleasure of living.
"He deprived Anelisa's grandmother and Yonelisa and Zandile's mothers from the pleasure of caring for them, loving them, and leading them to adulthood," he said.
Anelisa's grandmother was so shocked when she heard the news that she lost consciousness. Yonelisa's pregnant mother had to be hospitalised and their deaths devastated their families.
Coetzee said the children were still alive when Hadebe raped them and they must have suffered intense pain.
Two pathologists testified that the children had such severe genital injuries they would have needed reconstructive surgery, had they survived.
Coetzee said it was clear Hadebe was sober and in his right mind when he committed the crimes.
"The interest of society demand that he must be harshly punished. A clear message must be sent out to would-be murderers and rapists that such atrocious conduct will not be tolerated.
"The accused shows no remorse for what he's done. He persists a defence which is clearly false. He refuses to take responsibility for his deeds.
"This is totally unacceptable to members of the Diepsloot community. The community expect from this court that it impose a sentence which will protect their children against persons such as the accused," Coetzee said.
For the first time since the trial started Anelisa's grandmother Bongiwe Mcubuse managed to smile. She said she was satisfied with the sentence but would never be able to forgive him.
National Prosecuting Authority spokesman Nathi Mncube said Hadebe did not deserve to be called a human being.
"We need to send a clear message that this kind of behaviour will not be tolerated," he added.