Hisham Geneina, head of the Central Auditing Authority until his dismissal in March by President Abdel Fattah al-Sisi, was also ordered to pay a fine of 20,000 Egyptian pounds (around USD 2,000).
The retired judge's troubles began after he quoted a study by the authority based on 2012-2015 reports that calculated the cost of corruption at about 600 billion pounds ($66 billion).
The study highlighted the allegedly illegal acquisition of state-owned land by senior officials and businessmen from the tenure of toppled president Hosni Mubarak.
Today, a Cairo court sentenced him to jail, accusing him of "spreading false information aimed at disrupting public peace and order", a judicial source said.
More From This Section
Geneina was also ordered to post bail of 10,000 pounds pending an appeal hearing.
The retired judge faced an intense media campaign accusing him and his family of tarnishing Egypt's image and of membership of the banned Islamist opposition.
In the trial that opened in June, the prosecution accused Geneina of "spreading false news with the goal of harming public interest" and of using "baseless calculations" to exaggerate the cost of corruption.
"Putting Egypt's top auditor on trial sends a clear message: the Egyptian government is waging a war not against corruption but against those who fight against it," Transparency International said last month.