"Participants noted that the global campaign against ISIL/Daesh is beginning to show results. The ISIL/Daesh advance across Syria and into Iraq is being halted," a coalition statement obtained by AFP said, referring to the group by its alternative names.
The statement said Iraqi and Kurdish forces, backed by coalition air strikes, "are now reclaiming territory in Iraq".
Signup to our newsletter and follow us on Facebook and Twitter!
The coalition of around 60 mainly Western and Arab nations was formed after the first US air strikes in August against IS, which has proclaimed a caliphate in parts of Iraq and Syria.
They also agreed at the Brussels meeting to develop a "multifaceted" strategy to combat IS, including stopping the flow of foreign fighters, cutting finance and "delegitimisation" of its powerful, social media-driven brand.
Kerry had earlier warned that the fight against IS could take "years".