Peacebuilding is, or at least was, at the heart of humanity’s quest for fusion; it still could be. This article analyses the peacebuilding implications of a ‘burning plasma’ fusion breakthrough, with its enormous implications for both worsening conflicts and for peacebuilding. To do so, we apply the nonkilling global political science peacebuilding conceptual framework; the quintuple helix technology innovation ecosystem model, emphasizing the role of civil society and socioecology; and recent path dependence theory. The first burning plasma will be a nearly unprecedented historical event. The closest parallel is the Trinity Test, which heralded the Atomic Age, the implications of which for perpetuating conflict and potentially for peacebuilding were keenly understood; we analyse the Test in path dependence terms for the first time to compare it with fusion. As with fission power, fusion will be weaponized due to its intrinsic benefits. However, the innovations leading to the burning plasma are not occurring in a vacuum. Unlike Trinity, which was conducted in secret in wartime without civilian or media contributions, fusion is being developed in peacetime in the public eye, and in the context of a low-carbon transition. With fission, immediately following the Second World War, despite initial progress, the USSR rejected the US Baruch Plan to put atomic energy and weapons under the UN to stifle a nuclear arms race, due to an insufficient political imperative to cooperate. The result was the Cold War. As such, we forecast a global critical juncture in which a new normative nuclear order can be created via a ‘new Baruch Plan’, with governments, the private sector, the International Energy Agency, the IAEA, and civil society accelerating the development and commercialization of fusion power. Moreover, if the world does finally enjoy ‘energy for all’, the expected decrease in interstate conflict opens up the possibility of a Universal Global Peace Treaty, with humanity re-prioritising its goals for this century.