The woman was radicalized with the help of her husband, police said in a statement, and allegedly wanted to go to Syria to become a jihadist.
Italy's anti-terror squad, Digos, monitored communication between the pair over social media, which they allegedly used to exalt terrorism.
Alongside a photo of her wearing a black niqab, the woman wrote on Facebook: “Only my body lives here, while my soul and thoughts are in a very distant place.
“Oh Allah, I ask for a death in your path, and I ask for death in the country of your prophet...heaven, heaven, heaven...I swear, I can't wait.”
Her 30-year-old husband had “liked” the posts, and others, referring to "jihad", police said.
The couple married in a civil service in December last year, after having wed in an Islamic ceremony in 2010.
Investigators also seized various material from their computers as well as the woman's travel documents.
In May, Italy deported a couple who were accused of sharing the terrorism ideology of their two sons, one of whom was killed while fighting for Isis in Syria. The other son was arrested in late April as part of a probe into international terrorism.
Around 88 people, believed to be a security risk, have been deported from Italy since the start of 2015.
Italy upped security across the country in the wake of the terrorist attacks in Paris last November.