The women, who had been jailed since late October, were instead given suspended sentences of one year. In addition, seven underage girls who had been sentenced to a juvenile detention facility until they turned 18 were placed on probation.
Human rights activists hailed the decision, but said the heavy jail terms should never have been handed down to begin with.
In the five months since Islamist President Mohamed Morsi was ousted in a military coup, thousands of his followers have been jailed for taking part in protests demanding his reinstatement. Lawyers for the women and girls said they had not engaged in any illegal act.
Authorities had accused them of property destruction, violent attacks on security forces and “instilling fear” in bystanders. However, public opinion was galvanized by photos and video footage of the 21 women and girls sitting quietly in the defendants’ cage, wearing white headscarves.