The former president who was ousted in 2013 had already been sentenced to 20 years in prison on other charges. The country's highest religious authority will still review the penalty.
It was the second court to give the same sentence after the earlier conviction was overturned. The latest ruling can be also be appealed, Mubarak's attorney says.
The election pits interim President Moncef Marzouki against challenger Beji Caid Essebsi, who held a post in the ousted regime of Zine El Abidine Ben Ali.
It is not clear if the former strongman, who was ousted after massive anti-government protests in 2011, will walk free as he is also serving a separate 3-year sentence.
When Tunisia's young people protested in 2011, they had one key demand: jobs. Now, despite new political leadership, that demand remains unmet — even in tech, the sector that offers the most promise.