They drove away from the training unit at the rear of the prison complex in an Audi A5 coupe – worth around €50,000.
He will be back in prison on Thursday and is due for full release in early January.
Once the country's richest businessman, Sean Quinn was jailed for contempt of court last month.
He may yet get to attend the Christening of his granddaughter while on three days temporary release from his nine-week sentence.
A High Court judge told him she had no choice but to sentence him, amid allegations of a scheme that put the family's €500m international property empire beyond the reach of the former Anglo Irish Bank.
Quinn Jr was recently released following a three-month sentence in the same prison for contempt.
Sean Quinn Sr will spend the three days and nights with his family in Ballyconnell, Co Cavan, following a complex legal wrangle involving the Attorney General, the Justice Minister, the Irish Prison Service and the governor of Mountjoy prison. His temporary release follows an impassioned plea on behalf of his wife Patricia, who could not bear to be separated from her husband at Christmas.
In letters to prison authorities and the State, Quinn's family said that in almost 40 years, Sean and Patricia Quinn had never spent a Christmas apart.
When news that the temporary release was granted came through, Sean Quinn Jr said his family were delighted that his father would be home for Christmas. "We were waiting all day and we didn't know which way it would go," he said.
It was initially thought that Quinn would have missed the christening of his granddaughter Orna, which was due to take place in Belturbet, Co Cavan, on Saturday.
But there were no indications that the christening went ahead over the weekend in the church where many of the Quinn family weddings took place.
Sources close to the family suggested that it may have been postponed in order to allow Sean Quinn to attend.
In the run up to his temporary release, his daughter Ciara Quinn told Mountjoy governor Ned Whelan in a letter that the birth of her daughter in August was "the only good in my life over the past 19 months".
She said that not having her father at the christening "will leave a large void in the ceremony and a dark cloud over the entire day".
Prisoners held for contempt can only be released by the courts but Quinn's legal team provided legal submissions to the Attorney General, Marie Whelan and Justice Minister Alan Shatter.
Kevin Winter, the Belfast-based human rights lawyer who represented Quinn at his sentence hearing, said: "It is right and fitting that he be granted that facility because it is no more or less than that enjoyed by many other prisoners at this time."