The 26-year-old was formally charged with one count of murder after the body of the 29-year-old model was found at the sprinter's home in Pretoria with gunshot wounds to the head and the upper body.
A joint statement from Pistorius's family and management company said: "Firstly, and most importantly, all our thoughts today must be with the family and friends of Reeva Steenkamp. Oscar Pistorius has appeared in court here in Pretoria this morning formally charged with the murder. The alleged murder is disputed in the strongest terms.
"Oscar Pistorius has made history as an Olympic and Paralympic sportsman and has been an inspiration to others the world over. He has made it very clear that he would like to send his deepest sympathies to the family of Reeva.
"He would also like to express his thanks through us today for all the messages of support he has received, but as stated our thoughts and prayers today should be for Reeva and her family, regardless of the circumstances of this terrible, terrible tragedy."
The double amputee will remain in custody at a police station until Tuesday, when his defence lawyers are expected lodge an application of bail.
The prosecution said in court that they believe there is enough evidence to suggest premeditated murder.