Steenkamp's father Barry said he was "very glad" the seven-month trial was over, Independent Online reported.
The Steenkamps' lawyer, Dup de Bruyn said that the sentence Judge Thokozile Masipa handed down would likely be served as two years in prison and three years under house arrest.
"In effect he gets three years' correctional supervision and two years' direct imprisonment," De Bruyn said.
Steenkamp's mother, June turned to a family friend, Gina Myers, to thank her for her steadfast support throughout the trial before leaving the courtroom.
Meanwhile, the African National Congress's (ANC) Women's League said that Pistorius's sentence signalled a sad day for women in South Africa.
"We are saddened by the judgment, we have never been happy with the conviction of culpable homicide, instead of murder," ANC Women's League spokeswoman Jacqui Mofokeng said.
"We call for the national prosecutions to appeal this sentence."
She said Pistorius could be out within 18 months.
"If he serves 18 months, he could be out soon after that, while Reeva is not here, women are saddened by this."
Pistorius was also sentenced to three years for firing a pistol under a table at Tasha's restaurant in Johannesburg in January 2013.
Further, he was found not guilty of shooting through the open sunroof of a car in Modderfontein Sep 30, 2012, and of illegal possession of ammunition.
Pistorius was taken to prison after the sentencing.