The Cairo Criminal Court sentenced political activist and blogger Ahmed Douma to 15 years in prison, after a retrial on Wednesday.
Family and friends weeped as the judgement was read out.
Douma was also fined six million Egyptian Pounds ($335,000; €290.000) over his role in a Cairo protest in December 2011, in which a science academy was set on fire.
He appealed a 25-year sentence he was handed in 2015 for violating a law which banned unauthorised protests.
It was upheld on appeal in July 2017, but was overturned by the Court of Cassation, which ordered the subsequent retrial.