The six-time Paralympic gold medallist killed his girlfriend Reeva Steenkamp by firing four gunshots through a toilet door at his home in Pretoria on Valentine's Day last year.
The 27-year-old sat in the dock with his head slumped while the judge delivered her verdict at the High Court in South Africa.
The court heard that there was no evidence to prove that Pistorius was guilty of premeditated murder, as well as second degree murder.
However, Pistorius could face a maximum sentence of 15 years in prison if he is found guilty of culpable homicide (manslaughter).
The athlete has maintained that he mistook Steenkamp for an intruder when he fired the gun.