The firearm, a nine-millimeter Glock pistol with a magazine, was found by police officers Monday during a vehicle stop in the capital Brasilia.
The decision by Judge Alexandre de Moraes, seen by AFP, said Bolsonaro will be questioned at his home on Tuesday.
The 71-year-old former president is serving a 27-year sentence for plotting a coup over his attempt to cling to power after losing the 2022 elections to President Luiz Inacio Lula da Silva.
He has been under house arrest since March to recover from pneumonia, though the terms of his incarceration are set to be reviewed next week.
The man found with the gun registered to Bolsonaro said he was a part of the former leader’s security team and said he was transporting it to receive repairs.
A document submitted to the court, seen by AFP, said Bolsonaro’s security team had removed the gun’s firing pin — rendering it unusable — without informing Bolsonaro due to “psychiatric medications that had been administered to the Petitioner, capable of affecting his cognition.”
Attorneys for Bolsonaro said the weapon was legally registered under his name and kept at his residence, but denied it had anything to do with the upcoming deadline for his house arrest term.
Bolsonaro had been under house arrest last year but was returned to jail in November after he burned his ankle monitoring bracelet with a soldering iron, which the court interpreted as an attempted escape.
His lawyers at the time said the incident was due to mental confusion caused by medications he was taking.
