Islam Gawish, known on social media networks for his cartoons mocking Egyptian officials, was arrested on Sunday, in a move that raised fresh alarm over freedom of expression in Egypt.
"He has been released after interrogation," his lawyer Ahmed Abdel Raham told AFP.
The prosecution service confirmed that Gawish had been freed without any charges.
Gawish was arrested at work, the office of a local information website that operates without the required legal permits, the interior ministry said in a statement on Sunday.
It said he was detained for "administering a personal site on the Internet without a licence in violation of the law", and also accused him of using pirated computer software.
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Gawish's cartoons are posted on a Facebook page followed by more than 1.6 million people. He also runs a website.
A joint statement by several small opposition parties had demanded the cartoonist's "immediate release", and had denounced what it called a policy of "restricting freedom of opinion and expression adopted recently by the state apparatus".
"We warn about the consequences of a return to the police state and the repression of freedoms," said the statement signed by eight parties including the liberal Al-Dostour, founded by Nobel Peace laureate Mohamed ElBaradei.
Since Sisi overthrew his Islamist predecessor Mohamed Morsi in 2013, the authorities have been accused of cracking down on all forms of opposition.
Gawish's arrest coincided with the fifth anniversary of the 2011 popular uprising that forced strongman Hosni Mubarak to step down after three decades in power.
In the aftermath of Morsi's ouster, more than 1,400 Islamist protesters demanding his reinstatement were killed by police and soldiers, and more than 15,000 jailed.
Initially targeting Morsi supporters, the police crackdown has been extended to include secular and leftist movements.