Defence lawyers argued that Smith, 40, wasn't a member of Islamic State, and only went to Syria to become a wife and mother.
Irish ex-soldier Lisa Smith has been convicted of membership of the Islamic State (IS) terror group, a court in Dublin has ruled.
Smith, who left the army in 2011, was found to have been a member of the Islamist militant group between at least 28 October 2015 and 1 December 2019.
Judge Tony Hunt of the Special Criminal Court ruled that contrary to her plea of not guilty, Smith had knowingly travelled to an area of Syria controlled by IS in 2015 after converting to Islam.
She had previously made a pilgrimage to Mecca in 2012 and expressed on Facebook her desire to live under Sharia law and die as a "martyr".
Smith, who was in the army for 10 years, was also accused of moving to Raqqa, Syria, which was then controlled by IS, and marrying a British man who took part in armed patrols for the terror group. She was deported with her two-year-old daughter after the fall of IS in 2019 and arrested at Dublin Airport.
At the close of the nine-week trial, Smith was, however, was found not guilty of financing a terrorist organisation over an €800 donation she had said was for humanitarian purposes.
The money, she said, was to contribute to the medical treatment of a Syrian national in Turkey. She burst into tears when the decision was announced on Monday morning.
She will be sentenced on Monday, July 11.