The term “energy sovereignty” is used with differing emphases to describe a State’s rights or assertions over energy resources and supplies. Given the importance of offshore energy developments, particularly in the field of renewables, this article explores the meaning of energy sovereignty, arguing that more complex, cooperative approaches towards sovereignty are required in order to adapt to the nature of energy and energy demands. This approach is particularly important in the context of marine resources, where there is shown to be a carefully crafted balancing of interests between coastal States, third States and community interests. The article further suggests that in order to help explain energy sovereignty against this complex background, recourse may be had to theories of justification of ownership of resources. The example of natural rights-based approaches is used to show how this can inform the direction that legal regimes might take.