In December 2022, a scientific breakthrough in fusion energy resulted in widespread media attention with a focus on fusion as a key strategy to mitigate climate change. In this article, we draw from Herbert Marcuse’s work on technological rationality to examine fusion technology in this context. We explore if fusion is seen as a way to master nature, if it protects current power relations, and if a focus on fusion might detract attention and resources from alternatives. Illustrating technological rationality, much attention is being given to the potential achievement of fusion energy, it is being championed by already powerful economic actors, and despite that it is unlikely to be ready in time to support necessary climate mitigation, it may be detracting support for more effective and just strategies that already exist. In this context, framing fusion as a solution to climate change represents what Marcuse calls ‘one-dimensional thinking’.