Former French Prime Minister François Fillon was prime minister under President Nicolas Sarkozy between 2007 and 2012.
The judgement concluded Fillon paid his wife and children, as well as Joulaud, hundreds of thousands of euros from the public payroll for little or no work.
Fillon was sentenced to five years in prison, three of them suspended, as well as a fine of 375,000 euros ($423,000) and a ten -year ban on running for elections.
His wife Penelope was sentence to a suspended prison sentence of three years and a fine of 375,000 euros.
The Fillons and their co-defendant were also ordered to reimburse more than one million euros ($1.13 million) to the French National Assembly.
"This decision ... is not fair and we will appeal," Antonin Lévy, Fillon's lawyer told BFM-TV
. "There will be a new trial. In the past few days we have started to understand the ludicrous conditions in which this investigation was launched."
Fillon was prime minister under President Nicolas Sarkozy between 2007 and 2012.
His problems began in 2017 when French satirical newspaper Le Canard Enchainé published reports that his wife and two of his adult children earned nearly 1 million euros as parliamentary assistants for the alleged fake jobs.
He rejected the claims at the time, saying his wife worked for 15 years as his deputy and handled several roles, including managing his schedule and representing him at cultural events. He also said his daughter and son were employed in similar positions for 15 months and six months respectively, which he said is not illegal, but was an "error of judgment."
The scandal derailed his campaign for the French presidency in 2017 and gave way for Emmanuel Macron's victory.