of culpable homicide after a 2008 road accident in which a woman motorcyclist sadly lost her life," the family said in a statement.
His trial had been due to start last Thursday, a day before his Olympic and Paralympic hero brother, was granted bail on a charge of premeditated murder over the Valentine's Day killing of his girlfriend Reeva Steenkamp.
But his case has been adjourned to the end of March, meaning he will likely go on trial before his younger brother.
The 28-year-old Carl "deeply regrets" the incident, the family said. "It was a tragic road accident after the deceased collided with Carl's car."
He had no alcohol in his blood at the time of the accident, according to tests, the family added.
Prosecutors reinstated the charges after they were initially dropped. Attorney Kenny Oldwage, who also represents Oscar Pistorius, had "no doubt" Carl was innocent, the statement added.
The eNews Africa TV channel reported the accident happened in Vereeneging 60 kilometres south of Johannesburg.
Oscar Pistorius, the 26-year-old double amputee athlete known as "Blade Runner", was released on one million rand ($112,770) bail on Friday. He is due back in court on June 4.
He says the shooting of his 29-year-old girlfriend, a law graduate and cover girl who he had been dating since late last year, was an accident and that he mistook her for a burglar.
Carl Pistorius, whose last known job was as at an events management company in 2010, was a constant presence in court last week to support his brother during four-day bail hearing in Pretoria, along with his sister Aimee and father Henke.
When Oscar broke down crying in the dock, Carl would lean forward and put his hand on his brother's shoulder.
Relatives of the slain model have lashed out at the Pistorius family, with her uncle Michael criticising them for failing to contacting the Steenkamp family after the shooting.
"They have not offered their condolences, nor made a simple phone call to us," he told the City Press newspaper on Sunday, although the Pistorius family did send a bouquet of flowers and a card.
Meanwhile, City Press said a substance found in Pistorius's luxury Pretoria home during a police search was an over-the-counter herbal sexual stimulant.
The prosecution had said during Pistorius's bail hearing that police found two boxes of "testosterone" and needles, but the defence countered that it was a legal herbal remedy known as testocompasutium coenzyme.
City Press said the remedy was a combination of vitamins, herbal cures partly derived from animal organs.
Sports physician Jon Patricios told the paper the product is used to boost sexual energy, but athletes are not advised to use it since it may increase their testosterone levels.
"This is not an anabolic steroid and it is unlikely it will lead to irrational anger," he said.
The National Prosecuting Authority said it was awaiting results of forensic tests to determine what the product is.
The International Paralympic Committee said the athlete – who became a hero as the first double amputee to compete in the Olympics last year – was tested twice during the London Paralympics in 2012 and tested negative.
South Africa's Sunday Times newspaper also said a new investigation team had visited Pistorius's house on Friday and would investigate his apparent links with a network that used recreational drugs.
City Press also said the Steenkamp family has hired a private eye to follow the probe into her killing, quoting the investigator Lance Epstein.
Since the shooting, Pistorius's career has come to a halt and he has lost endorsement contracts with Nike, sunglasses maker Oakley and French cosmetics firm Clarins.
Despite his success on the track, he has had a rocky private life with stories of rash behaviour, beautiful women, and a love of guns and fast cars.