REUTERS/Mike Hutchings
Dressed in a dark suit, the 29-year-old hugged members of his legal team in the packed Pretoria court room. He then took his seat and was seen tapping away on his mobile phone.
Pistorius was found guilty of murdering Steenkamp by an appeals court last December. He had initially received a five-year sentence for a manslaughter conviction in 2014, a ruling derided by women's groups as too lenient.
The athlete had the lower part of his legs amputated when he was a baby and his lawyers have argued that his disability and mental stress should be considered as mitigating circumstances to reduce his sentence.
The state says he has shown no remorse and has called for him to receive no less than the minimum 15-year sentence for murder.
The original trial judge, Thokozile Masipa, will deliver the sentence.
The length of any jail term depends on how she will weigh the role of his disability in the killing and the time Pistorius has already served in jail as a result of his original conviction.
Pistorius was freed from prison last October after almost a year behind bars to serve out the remainder of his term under house arrest at his uncle's house in a wealthy suburb of the capital.
Some rights groups have said Pistorius, a wealthy white man and international celebrity, has received preferential treatment compared to others without his status or wealth.
Outside the court, a group of people held up placards backing the athlete. One read: "Give Oscar his freedom back please".
Steenkamp's mother and father, who said Pistorius had to pay for his crime, were also in the court.
Members of the Women's League of the ruling African National Congress, who have attended the trial in support of the murdered Steenkamp clad in their green and black uniform, were seated in court awaiting the ruling.
Johannesburg-based lawyer Ulrich Roux, who is not involved in the case, said Masipa would have to balance any mitigating circumstances against the seriousness of his crime.
"For her it's a delicate balancing act," said Roux, adding that either the defense or prosecution could mount a legal challenge if they felt the sentence was too lenient or harsh.
Department of Correctional Services spokesman Manelisi Wolela said Pistorius would be taken to jail immediately after sentencing.