The former Olympic and Paralympic runner was denied parole because he has not served a “minimum detention period”, authorities in South Africa said following a hearing on Friday.
Pistorius, a multiple Paralympic champion who made history by running against able-bodied athletes at the 2012 Olympics, was convicted of murder for the Valentine’s Day 2013 shooting of Ms Steenkamp, 29, at his home in Pretoria.
The 36-year-old claims he shot Ms Steenkamp by mistake, thinking she was an intruder.
He said he did not realise she got out of bed and went to the bathroom.
Pistorius was sentenced to 13 years and five months in prison and is eligible for parole under South African law after serving half his sentence.
A parole hearing was held on Friday at Atteridgeville Correctional Centre in Pretoria, where Pistorius has been held since 2016.
The decision was expected to take days to finalise.
Double-amputee Pistorius fired four shots with his licensed 9mm pistol through a toilet door at his upscale Pretoria home to kill Ms Steenkamp, who was also a reality TV star, in the early hours.
He was ultimately sentenced in 2017 after a series of appeals and has, taking into account time served, served more than seven years since late 2014.
An initial manslaughter conviction was overturned after an appeal by the prosecution and replaced with a murder conviction.
Ms Steenkamp’s parents had been expected to oppose Pistorius’s parole application.
Their lawyer Rania Koen said unless he “comes clean” about the deadly shooting of his model girlfriend, her parents “don’t feel that he is rehabilitated”.
Barry and June Steenkamp believe he killed her intentionally after a late-night row.
Ms Koen said June, who hails from Blackburn, Lancashire, would submit written and oral statements at the hearing to oppose Pistorius’s bid for freedom.
“She doesn’t feel that he must be released,” Ms Koen told reporters outside the Atteridgeville Correctional Centre.