The women, all reportedly young mothers, had been held in an island prison on the Red Sea since last August.
They were arrested in 2017 after a series of raids on underground churches by the Eritrean authorities. Many of their husbands were conscripts, leaving their children without anyone to care for them, human rights group Release International reports.
They are the latest Christians to be freed from prison in a string of unexpected prisoner releases over the past half year.
Last month, 70 Christians from evangelical and orthodox backgrounds were freed, and another 27 last September. In total, 171 Christians have been freed since last August.
There are still around 130 Christians in Eritrean prisons and an unknown number of Army conscripts locked up for practicing their faith. A further 150 Christian prisoners are believed to be detained by the Army, but little is known about them, Release said.
Although the charity has given a cautious welcome to the prisoner releases, it warns that this good news is being overshadowed by attacks on churches in Tigray by Eritrean forces.
A massacre in the sacred city of Axum killed an estimated 800 people, including many priests and church members.
The attack involved the Church of St Mary of Zion in Axum, which Ethiopians traditionally believe is home to the Ark of the Covenant, which held the Ten Commandments.