Mubarak, 84, and seven others had been on trial for the past 10 months for their management of a revolution that began early last year and resulted in at least 840 civilian deaths.
Judge Ahmed Refaat sentenced Mubarak and former Interior Minister Habib El Adly to life in prison Saturday, but cleared six former police commanders of their charges.
A state-run television station said Egypt's public prosecutor on Sunday began the process of appealing the court's decision, Ahram Online reported.
Meanwhile, a second day of protests began Sunday in Cairo after the verdict was read.
Protester Sharif Ali told the BBC he was angry over the six acquittals and the two life sentences.
"When they return to court on appeal, they will be freed too," Ali said.
Mubarak could have faced the death sentence.
The public anger is likely to affect this month's presidential run-off elections, CNN reported.
Former air force officer Ahmed Shafik -- Mubarak's last prime minister -- is expected to suffer losses by his association with Mubarak in his race against Mohamed Morsi, the candidate for the Islamist coalition group Muslim Brotherhood.