European foreign policy chief Federica Mogherini announced on Tuesday morning that ministers had agreed to support France, which has intensified bombing raids against the terror group's stronghold in Syria and Iraq.
His appeal came after Friday's bloodshed in Paris – the worst ever terror attacks on French soil.
It is the first time that a European Union member state has invoked the article, which is similar to Nato's article five which the United States activated after the September 11th, 2001 attacks and triggered the alliance's intervention in Afghanistan.
Jacob Westberg, Senior Lecturer in Security Policy and Strategy at the Swedish National Defence College said: "The article is relatively clear and says that states must contribute by all available means. Hollande is trying this track and it will be interesting to see how other countries respond."