Amnesty International said the sentences, linked to clashes in 2013 between security forces and supporters of ousted Islamist president Mohamed Morsi, amounted to “a mockery of justice”.
Photographer Mahmoud Abu Zeid was among 739 defendants on trial, most of them charged with killing police and vandalising property.
The journalist, widely known as Shawkan, was arrested as he covered the clashes that turned into a bloodbath in which hundreds of demonstrators died.
The court also confirmed death sentences initially passed in July against 75 defendants, including leaders of Morsi’s outlawed Muslim Brotherhood such as Mohamed el-Baltagui, Issam al-Aryan and Safwat Hijazi.
Of the 75 defendants facing the death penalty, 44 were in the dock while the rest were tried in absentia.
Forty-seven were handed life sentences, while 347 were given 15 years in prison, and 22 minors received 10-year terms.
The court sentenced Morsi’s son, Ossama, to 10 years in jail, while 215 people were handed five-year prison terms.
‘Disgraceful mass trial’
In a statement, Amnesty condemned Saturday’s death sentences and heavy prison terms after what it called a “disgraceful mass trial”.
The rights watchdog called for a retrial in front of an “impartial court”.
It said the verdicts were “a mockery of justice”, since “not a single police officer has been brought to account”.
Shawkan, who earlier this year received UNESCO’s World Freedom Prize, is expected to walk free within days because of time served, his lawyer said.
He was accused of “murder and membership of a terrorist organisation” — charges that can carry the death penalty — but has already spent five years in jail.
Smiling in the dock, the photojournalist made a “V” for victory sign, while his lawyer, Karim Abdelrady, said he would launch a legal bid to have the conviction overturned.
His detention sparked outrage among human rights groups and NGOs who lobbied continuously for his release.
A photo of Shawkan — behind bars with his hands in front of his face mimicking holding a camera — has circulated widely on social media.
Amnesty said he had been convicted “simply for doing his job as a photojournalist and documenting the police brutality that took place that day”.
Reporters Without Borders (RSF) ranks Egypt 161st out of 180 countries on its press freedom index and says that at least 31 journalists are currently detained in the Arab world’s most populous nation.
About 700 killed
On August 14, 2013, one of the bloodiest days in Egypt’s modern history, a month after the army ousted Morsi, police moved to disperse a sprawling Islamist protest camp at Rabaa al-Adawiya square in Cairo.
About 700 people were killed within hours at that site and Nahda Square where another sit-in was being held.
Hundreds more were killed in street clashes with police over the months that followed and mass arrests were made.
Amnesty and Human Rights Watch say at least 40,000 people were arrested in the first year after Morsi’s ouster on July 3, 2013.
Egypt’s courts have sentenced hundreds of them to death or lengthy jail terms after other speedy mass trials, including Morsi and several leaders of his Brotherhood movement.
Former armed forces chief Abdel Fattah al-Sisi won the presidency in 2014 after leading the ouster of Morsi following mass protests against the Islamist’s rule.
Sisi won re-election with 97 per cent at a vote in March against a single opponent widely seen as a token challenger, with critics saying the president had carried out a widespread crackdown on dissent.