Saida El Alami, 48, a vocal human rights activist with regular online presence until her arrest in March, had been handed a two-year jail term and a 5,000-dirham ($500 at the time) fine in April, in a case that sparked condemnation by international rights groups.
A Casablanca court had found her guilty of crimes including "insulting" government bodies and public officials, as well as "spreading false allegations". She denies the charges.
"Saida El Alami expressed herself in the context of her freedom of expression, which is enshrined in the constitution," defense lawyer Souad Brahma told AFP, calling the appeals court's ruling "unjust."
The activist's defense team said it plans to appeal once more to the Court of Cassation, whose ruling would be final.
El Alami, who describes herself as a "political dissident" on Facebook, had criticized security forces and accused the judiciary of corruption, according to Amnesty International.
She had also spoken out in support of imprisoned Moroccan journalists and activists.
Following her arrest, Amnesty called on Moroccan authorities "to end the prosecutions of activists who have been critical of public figures, state officials or state institutions, and to ensure that people are free to express their opinions without fear of reprisals."