Cairo's Criminal Court on Tuesday also confirmed death sentences on a number of leading members of Morsi's Muslim Brotherhood group, including its general guide Mohamed Badie.
More than 80 accused were sentenced to death in absentia, according to Reuters.
The sentences had been pronounced by the court last month but required examination under Egyptian procedures by the country's most senior religious authority, Grand Mufti Shawqi Allam.
Tuesday's sentencing is still subject to appeal.
Morsi and others, who were freed from internment during the chaos of 2011, had faced charges of conspiring with foreign Islamist groups to organize prison escapes and kidnapping and killing police officers.
Egypt's long-time ruler, Hosny Mubarak, was topped in that uprising.
The proceedings that led to Tuesday's ruling were dismissed by the Brotherhood as a political farce.
Mursi, dressed in a blue prison suit, smiled slightly as the judge read out the sentence. Other defendants chanted "down with military rule."
Jail term for Morsi in second case
Earlier on Tuesday, the same court had sentenced Morsi and 16 others to long jail terms on charges of spying for the Palestinian Hamas movement, Lebanon's Shiite Hezbollah, and Iran.
Morsi became Egypt's first democratically elected president - after Mubarak's ouster - but was overthrown by the army in July 2013.
Army head Abdel-Fattah el-Sissi was subsequently elected president.
Authorities then cracked down heavily on Morsi supporters, leaving at least 1,400 people dead and more than 40,000 in custody, according to Human Rights Watch.
The crackdown also extended to secular and leftwing activists, who spearheaded the 2011 revolt against Mubarak. Dozens were jailed under a law that bans all but police-sanctioned demonstrations.
Trial slammed as 'unjust', 'unfair'
Amnesty International described the Cairo trial proceedings against Morsi and other defendants as "grossly unfair."
Turkey last month warned tht the Middle East would be thrown into turmoil if Egypt carried out the death sentences.
The US State Department described the Egyptian court's ruling as "unjust."
Al-Sissi, while on a visit to Germany earlier this month, was told by Chancellor Angela Merkel that Germany opposes the use of the death penalty.