The marine environment has long been a major source of energy across the globe and will continue to be central to future energy provision to meet growing human demands. Historically, energy has been extracted in the form of fossil fuels from below the seabed, but more recently there has been an increase towards harnessing renewable energy resources. While these industrial-scale activities generate power in different ways, they can all potentially degrade the surrounding environment. At present, understanding how the localised extraction of energy affects the marine environment is highly uncertain. Although some information exists, the available evidence is patchy and incomplete such that optimal decision making is difficult. Furthermore, most of the available evidence relates to direct effects on a few particular species or habitats. There is also a tendency to report only the negative effects, principally driven by targeted environmental impact assessments. Unanswered questions often remain about whether the effects recorded are biologically meaningful. To determine if a negative impact has occurred requires considering both direct and indirect effects, identifying pathways of effects, and taking into account the spatial and temporal scales over which changes occur. Properly considering the demonstrable effects of predicted impacts over a wide range of spatial and temporal scales is fundamental to the development and understanding of cumulative environmental effects arising from offshore energy development. Accounting for cumulative effects is essential for the sustainable use of the marine environment and thus must be a central consideration in marine spatial planning processes. The results of cumulative impacts assessments underpin decision making by licensors, regulators and stakeholders. A robust and transparent process when assessing interactions and making planning decisions associated with cumulative environmental impacts will reduce conflict surrounding offshore energy development. As many countries aim to increase offshore energy development and improve the efficiency of the associated licencing processes, marine spatial planning will play a pivotal role by providing integrated process for the mitigation of user-nature as well as user-user conflicts.