The couple are accused of having “maliciously” caused three cooperative companies to go bankrupt after having emptied their coffers and illegally making millions of euros.
The cooperatives are connected to “Eventi 6”, the family business already under investigation for the disappearance of funds.
Gian Franco Massone, vice-chairman of one of the cooperatives, was also arrested.
The investigation was led by state prosecutor Giuseppe Creazzo, his deputy Luca Turco and investigating magistrate Christine Von Borries.
Magistrates requested the arrest of Renzi’s parents over concerns they might try to tamper with evidence or commit further offences.
Matteo Renzi confirmed on Monday commented on the arrest of his parents, both in their 70s.
In a Facebook post, the Democratic Party (PD) leader said his parents were being targeted because of his own political activities.
“People who have read the [investigative] papers assure me they have never seen such an absurd or disproportionate measure,” Renzi wrote.
“If I hadn’t entered politics, my family would not have been buried under this mud.”
Tiziano Renzi is a businessman and former local politician in the Tuscan town of Rignano sull’Arno.
He has found himself at the centre of several scandals since his son became prime minister in 2014.
Last year, he and his wife faced trial for allegedly issuing bogus invoices for their companies.
The case was due to be heard next month.
The couple have denied any unlawful activity.
Matteo Renzi last week published a book on his two-year stint as prime minister and was in Turin on Monday for a presentation when news of the house arrest broke.
He immediately cancelled the event.
