Driven from investments toward net zero transition global interest in fusion energy is growing. This policy perspective addresses challenges for its commercialization, given the potentially long timeframe to deployment and competing/complementary technologies. We focus on magnetically confined fusion power, specifically tokamaks, as the route to commercialization is clearer and there is some cost data available. For fusion to be competitive beyond 2040, costs will likely need to be at or below ∼$80–100/MWh at 2020 price. This will be hard to achieve for early fusion designs both small or large, for which modelling shows energy costs will be greater than $150/MWh even accounting for production learning. This is due to the low power availability from pulsed operation; frequent replacement of vessel components; and low efficiency power cycles. Technology improvements to improve both cycle efficiency and power availability, along with production standardization and long-life components, have the potential to reduce generation costs and enable magnetically confined fusion to be commercially viable. We therefore recommend focusing commercialization efforts on plants with higher thermal efficiency and potential for higher availability as these maximize the probability of fusion energy proving commercially viable. We also recommend that fusion energy be deployed within a proportionate regulatory regime that recognizes its relatively low radiological hazard. Finally, construction of fusion reactors should be planned in fleet/program terms, as commitment to constructing many units will be necessary for it to become commercially viable.