Abdel Fattah, who was arrested in February 2014, had initially been sentenced to 15 years in jail but a court ordered a retrial and he later received a sentence of five years in prison, of which he has served three and a half.
The court of cassation, which handles appeals in Egypt, upheld the five-year sentence but dropped an accompanying term of hard labour.
It also put Abdel Fattah, 35, on probation for five years after his term behind bars.
At the hearing, which was closed to the media, the activist was represented by lawyer Khaled Ali, another prominent figure in the 2011 revolt and critic of Sisi’s regime.
On Monday, Ali launched a campaign to run in Egypt’s presidential election planned for spring 2018.
Described as an “icon of the revolution” six years ago, Abdel Fattah was among dissidents arrested after a November 2013 protest outside parliament in defiance of a law that banned all demonstrations except those authorised by police.
Egyptian rights groups said his trial had been “full of violations of the law and without procedural safeguards”.
The case was among the most prominent in a series of trials of secular dissidents who have been jailed along with thousands of Islamists since the army overthrew Mubarak’s successor, Islamist president Mohamed Morsi, in July 2013.
