"He had acted with premeditation. He came prepared (to commit the crimes) and was always in control," The Times daily quoted Judge Rean Strydom as saying during sentencing.
Authorities said Morake threatened the women with a gun and sometimes tied up the partners of his victims and forced them to witness the rapes.
Strydom said Morake, who showed no remorse for his actions, behaved arrogantly and "provided his victims with advice on how to protect themselves from rape in the future".
According to South African law, Morake will not be eligible for parole before serving at least 25 years behind bars.