The 2011 Istanbul Convention aims to "prevent violence, protect victims and punish the guilty," Italian Foreign Minister Emma Bonino said.
The treaty has been signed by 25 Council of Europe member states but has so far only been ratified by Turkey, Albania, Portugal, Montenegro and now Italy.
It needs to be ratified by 10 countries - eight of which need to be members of the Council of Europe - for it to take effect.
Bonino said she would "continue an awareness campaign to encourage our partners to ratify the convention as quickly as possible so that it can enter into force."
The convention, which had already been approved by Italy's lower house of parliament, was adopted unanimously by the Senate on Wednesday.
Its measures to improve prevention and protection include "granting police power to remove perpetrators from the home" and improving resources such as "shelters, telephone hotlines, specialist support services, crisis centres, and legal assistance."
In 2012, some 120 women were murdered in so-called femicide attacks in Italy, and a third of all women here are victims at some point of domestic violence according to a UN report, which cites data from the national statistics agency (ISTAT).
A 2012 report by the Thomson Reuters Foundation comparing women's rights in the G20 countries highlighted femicide as being a particular problem in Italy. The country was however not alone in being criticized; India was defined as the worst G20 country for women, while violence against women in Mexico was especially high.
There have been dozens of cases reported of women killed by their husbands, boyfriends or former partners this year, as well as a spate of acid attacks which have stunned the European country.
Last month the body of 15-year-old Fabiana Luzzi was found in southern Italy, her boyfriend had allegedly stabbed her multiple times before setting her alight while Luzzi was still alive.
In May, Italy's speaker of the lower house of parliament Laura Boldrini called for a law to defend Italian women from misogynist and violent acts after receiving hundreds of menacing messages on the Internet, including photos altered to show her head on the bodies of women being raped or strangled.
She was defended by Italy's new equal opportunities minister, German-born Josefa Idem, who said that the "men, vile and without dignity, who consider it normal to insult and threaten a woman...are a sign of a subculture that must be uprooted in this country."
Earlier this month Italy appointed Isabella Rauti, the wife of Rome's former mayor Gianni Alemanno, as the government's advisor on the issue of violence against women.