The gathering stirred controversy after US Secretary of State Mike Pompeo billed it last month as a summit focused on confronting Iran, which he called a "destabilizing influence."
The hosts rowed back on their objective after EU foreign policy chief Federica Mogherini declined the invitation to the event and other nations showed little enthusiasm to attend it.
The agenda has since been broadened to promoting a future of peace and security in the Middle East and building a consensus on a stronger security architecture, according to the US State Department.
Ministers will address a range of critical issues, such as terrorism, missile development and proliferation, maritime trade and security, and threats posed by militant groups across the region.
The ministerial will start with a dinner hosted on behalf of Pompeo and his Polish counterpart, Jacek Czaputowicz.
Tunisia and Egypt are sending deputy foreign chiefs, while Turkey will be represented by its ambassador. UK Foreign Secretary Jeremy Hunt is expected for the opening. Other EU nations may be represented by lower-level officials.
Russia, Lebanon and Palestine bowed out of the conference, while Iran was excluded due to its strained ties with the United States, according to Polish Deputy Foreign Minister Bartosz Cichocki.
Cichocki argued that Iran’s or a similar point of view on the the way forward in the Middle East would still be presented and suggested making Iran part of the final solution.
Iranian Foreign Minister Javad Zarif slammed the meeting as an "anti-Iran circus," while Russia said the event offered a "simplified unilateral approach" to the Middle Eastern problem.