Scholarship on how speculative knowledges can contribute to envisioning sustainable futures is thriving. There is less attention to the specific ways in which political theory as speculative knowledge is relevant to these scholarly discussions. This article fosters this link by suggesting reading climate fiction as political theory. The article follows a four-step analysis. First, it clarifies the importance of pluralising and decolonising the knowledges through which climate change is engaged politically. Second, it introduces the concept of ecopolitical imaginary to capture collective visions for sustainable futures, showing the relevance of the theorising endeavour. Third, it elucidates the idea that placing political theory and climate fiction in dialogue can help envisage alternative ecopolitical imaginaries for future world ordering. Finally, it reads Robinson’s Ministry for the Future as an experiment in political thinking: an ecopolitical imaginary that helps to think through the challenges involved in countering the colonial logic of global climate governance and the Eurocentric universalism underpinning it. The overarching argument is that reading climate fiction as political theory offers insight into envisioning just sustainable futures.