The English former player turned journalist is believed to have jumped to his death from the sixth floor of his hotel in Cape Town, where he was covering the South Africa-Australia test series.
South African police said he was found dead outside his room at the hotel near Newlands cricket ground.
Police released a statement on Sunday confirming Roebuck had taken his own life on Saturday night, while Australia's cricket body said Roebuck had been with the Australian team just hours before his death.
Police spokesman Capt. Frederick van Wyk told The Associated Press it was suicide but would not give further details on the nature of the death and said he could not elaborate on reports that Roebuck had been questioned by police at the hotel earlier in the evening.
"I can confirm that an incident took place at about 21:15 last night where a 55-year-old British national who worked as an Australian commentator committed suicide," Van Wyk told the AP. "The circumstances around the death are being investigated."
Roebuck, a former opening batsman who captained the Somerset squad in the 1980s, wrote widely for the Australian press and also worked as a radio commentator for the Australian Broadcasting Corporation. After ending his playing career, he moved to Australia but also spent much of his time in South Africa.
In 2001, Roebuck pleaded guilty at a court in England on three charges of common assault involving three 19-year-old South African men who had been staying with him. He was given a suspended jail sentence of four months for each charge.
A report by the Sydney Morning Herald, one of the newspapers Roebuck wrote for, said he had been questioned at his hotel at about 9 p.m. on Saturday night by a uniformed police officer and a detective over an alleged sexual assault.
The newspaper said Roebuck was in an "agitated" state and suggested one of the police officers was still in his room when Roebuck jumped to his death. It was also reported that police removed personal items, including a laptop, from Roebuck's hotel room.
Police would not comment on any of those details.
"Peter was a familiar face around Australian cricket who had been with the team only hours before his sudden death," Cricket Australia chief executive James Sutherland said. "He bought particular insight to his commentary based on his lengthy experience as a first-class cricketer and captain, and combined that with a singular flair for the written and spoken word.
"He spoke his mind frankly and while one didn't necessarily always have to agree, you always respected what he had to say."
Cricket South Africa also offered its condolences and said it had lost "a good friend."
South African-born former England test captain Tony Greig, who also made the transition from player to commentator, said on Twitter: "The death of Peter Roebuck leaves the grass less green and cricket without its most effective investigative journalist."
