Others receiving the death penalty after court hearings included the former prime minister and the head of the country’s intelligence services.
The former officials were found guilty of committing war crimes during the 2011 unrest, including inciting the murder of peaceful demonstrators.
Saif Islam Gaddafi was sentenced in absentia, as he is held in the Libyan city of Zintan by local forces who refuse to comply with Tripoli's government.
Libya has been in a civil war since the 2011 overthrow and murder of Muammar Gaddafi. Currently there are two rival governments in the country, the internationally-recognized Libyan government in Tobruk and another in Tripoli.
On Monday, Tobruk's Justice Minister Mabrouk Ghraira called on the international community to not recognize the sentences, stating that the Tripoli trial was illegal.
