Lisa Smith has been charged and is expected to appear in court.
The former Defence Forces member was arrested on Sunday on suspicion of terrorist offences.
The 38-year-old, from Dundalk, Co Louth, was taken into custody after landing at Dublin Airport.
She was being quizzed at Kevin Street Garda Station.
Smith will be charged in Court 4 at Dublin District Court at the Criminal Courts of Justice on Wednesday morning.
A spokesman said: "The 38 year old woman detained at Kevin Street Garda Station has been charged to appear before a sitting of the District Court, Criminal Courts of Justice, today 4th December 2019."
Smith and her two-year-old daughter - both Irish citizens - were accompanied by two members of the Army Ranger Wing and officials from the Department of Foreign Affairs.
It's understood her child is now in the care of family members in Dundalk.
The former Defence Forces member converted to Islam in 2011, then quit the Air Corps and in 2015 travelled to Syria, through Tunisia.
It’s understood Smith was married four times and the child’s father was a British jihadi who was killed while fighting for ISIS.
Smith and her daughter were put into a camp for ISIS widows and children on the Syrian border.
She escaped last month following the Turkish invasion before she was picked up and handed over to Turkish officials
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