The top US diplomat arrived in Saudi Arabia's Red Sea port city of Jeddah and said "I'm confident" as he was greeted by the kingdom's foreign minister, Prince Saud al-Faisal.
Kerry will hold talks with counterparts from 10 Arab nations and Turkey hours after US President Barack Obama outlined his new strategy to confront the jihadists in a prime-time television address.
Steeling his nation for another foreign conflict, Obama pledged to expand US military operations against IS, a radical Islamist group that has seized a swathe of Iraq and Syria and committed horrifying atrocities.
"I will not hesitate to take action against ISIL in Syria, as well as Iraq."
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Obama announced the dispatch of another 475 military personnel to help train Iraqi forces to take on the Islamic State, bringing the total number of US troops in the country to 1,600.
But he made clear in the 14-minute address that the campaign will not be a repeat of the exhausting ground wars fought by US troops in the past decade.
"It will not involve American combat troops fighting on foreign soil."
Washington is instead looking to empower partners on the ground like the Iraqi forces, Kurdish fighters and Syrian rebels, to fill in territory opened up by US air power.
Key to that strategy will be improving the effectiveness of Syrian rebels, and Obama called on Congress to swiftly authorise an operation to train and equip moderate Syrian fighters.
"Many of the countries are already taking action against ISIL," a State Department official said.
"But the trip by the Secretary is going to broaden the coalition and bring it into more focus and intensify the lines of effort."
The official said Saudi Arabia would be especially important to the effort "because of their size and economic importance but also because of their religious significance with Sunnis."
The "train and equip programme" for Syria's rebels would be a particular talking point with the Saudis, the official added.