Climate disinformation and misinformation have turned into major challenges for city officials engaged in climate action by undermining trust in institutions and leaders. Falsehoods and lies undermine public support for action, discredit efforts for change, create confusion, and sow mistrust for climate solutions. The aim of disinformation is to erode public support for change at a time when climate impacts are becoming increasingly visible and people are calling for government actions and stronger policies. At the request of its Board Members, the Global Covenant of Mayors is taking a closer look at how to respond to disinformation. This paper explores current narratives of climate denial, explores best practices and proposes proactive strategies to counter misinformation by informing, engaging, inspiring, and empowering constituents expand public understanding and support for climate action.