The Paralympic champion shot dead the South African model through a toilet door at his home in Pretoria in the early hours of Valentine's Day last year.
Today, Judge Masipa has been delivering her verdict at the High Court following a six-month trial, but has dismissed the charge of premeditated murder.
She told the South African court: "The state clearly has not proved beyond reasonable doubt that the accused is guilty of premeditated murder. There are just not enough facts to support such a finding."
Pistorius is now facing a charge of culpable homicide or complete acquittal as the judge continues to deliver her verdict in court.
The six-time Paralympic gold medallist denies murder by claiming that he mistook Steenkamp for an intruder when he fired four gunshots through the locked door.