His forgery charges are deemed politically motivated.
The Lusaka Magistrate's Court on Wednesday jailed outspoken opposition leader Chishimba Kambwili for forgery.
Mr Chishimba, leader of the opposition National Democratic Congress, was a member of the ruling party, but fell out of favour and became critical of the President Lungu's regime before being fired as Information minister.
His forgery charges are deemed politically motivated as he was only arrested after the falling-out with the Patriotic Front.
He was found guilty of forgery and uttering of false documents.
“In the first count, the convict was sentenced to 12 months and another 12 months for uttering false documents, “said Magistrate David Simu Samba in his judgment.
The two sentences will run concurrently.
He was acquitted on one charge of giving false information to a public officer.
The conviction is a major setback to his presidential bid.
Opposition members have complained of the narrowing of democratic space, especially for those critical of the regime.
They claim the government is using state institutions to intimidate them ahead of the August 2021 general election in which the incumbent is controversially seeking a third term.