Lawyer Brian Webber said it had "become necessary" for the double-amputee runner to sell the villa in a gated community in Pretoria because his murder trial will go beyond the expected three-week duration.
Pistorius has never returned to the house since he fatally shot Ms Steenkamp in an upstairs bathroom in the pre-dawn hours of February 14 last year, Mr Webber said. He said Pistorius "cannot contemplate ever returning to live there again" and that the house has remained "sealed" since it was handed back by police over a year ago.
Pistorius is on trial at the high court in Pretoria charged with premeditated murder in Ms Steenkamp's shooting death.
In addition to the murder charge, the athlete also faces three other firearm-related offences. He has pleaded not guilty to all four charges.