The "American Beauty" star, 31, wed concert promoter Simone Sestito, 25, on Saturday in a private church in the holy city, according to TV Guide.
The pair got engaged in 2008 after meeting the year before at the Toronto Film Festival.
According to a People source, the intimate nuptials were "truly unique and Mena looked breathtaking."
The couple reportedly chose the destination wedding thanks to the groom's family members, many of whom are Rome-area residents.
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