Police said they had "instituted investigations" following a report of theft of three vehicles and "managed to locate the properties at Mrs. (Esther) Lungu's residence" in a suburb of the capital, Lusaka.
"The suspect has been summoned to appear before the police today," police spokesman Danny Mwale said.
Police said Lungu's wife allegedly "grabbed" the vehicles - a Mitsubishi truck, and two small Toyota sedans - from a woman in August last year.
The victim, who has been named but not further described, was made to surrender the vehicles after having been driven to the ex-first lady's residence, police said.
Scores of Lungu's supporters mainly from the former governing Patriotic Front party descended at the house in a show of solidarity to Lungu and his family, an AFP reporter saw.
Earlier, police were seen searching cars parked inside Lungu's yard.
In 2021 Lungu lost elections to President Hakainde Hichilema, who before winning the vote by a landslide was a veteran opposition leader.
Raphael Nakachinda, a spokesman for Lungu's party, accused Hichilema's government of harbouring "paranoia and anger and vindictiveness."
Zambia Raids Ex-President Over 'Stolen' Cars
FILE: Then-Patriotic Front (PF) Presidential candidate Edgar Lungu and his wife Esther Lungu leave a rally in Lusaka January 19, 2015.
LUSAKA - Dozens of heavily armed police officers on Wednesday raided the residence of Zambia's former president Edgar Lungu and impounded cars they said were allegedly stolen by the ex-first lady.