Egyptian activist freed after nearly two years without trial
Ali, as well as friends of Abdel-Fattah, posted photographs online of her being released from prison.
In 2008, Abdel-Fattah created an "April 6" Facebook page in support of striking workers and to call for political reforms, at the start of the mobilisation of mass protests that would lead to the toppling of president Hosni Mubarak three years later.
Abdel-Fattah, 43, was arrested in October 2019 on charges of "spreading false news" and "collaborating with a terrorist group".
Her detention sparked international condemnation, with the US calling it "scandalous".
Abdel-Fattah, who was also previously jailed under Mubarak, walked free just hours after a surprise decision by the prosecution to release her.
She had opposed the Muslim Brotherhood when they took power in Egypt in 2012 and backed the 2013 protests that led to the ouster of Islamist president Mohamed Morsi.
Under Egyptian law, pre-trial detention can be extended for up to two years.
On Saturday evening, the prosecution also decided to release activist Abdel Nasser Ismail, leader of the Popular Alliance party, who was arrested in September 2019 for "participation in a terrorist group", according to lawyers.
Egyptian journalist and opposition figure Gamal El-Gammal, arrested on his return from Turkey in February, was also freed.
The United States this week warned Egypt not to target rights campaigners, saying the issue would be a factor in arms sales to its ally.
Since President Abdel Fattah al-Sisi took power in 2014, the former army chief has launched a sweeping crackdown on dissent.