Invasive alien species are a major driver of global biodiversity loss. Constrained conservation budgets demand that threat abatement strategies take into account the heterogeneity of areas in need of protection, such as significant ecological and cultural sites, as well as the competing values, preferences, and objectives of stakeholders. We used strategic foresight to assess the threat that invasive alien grasses pose to environmental and Indigenous cultural values on the floodplains of a comanaged, World Heritage-inscribed national park. We found strategic foresight to be a useful framework to set management priorities that simultaneously conserve biological and cultural diversity. However, it required the development and application of novel ecological and participatory tools and significant time, financial, and human resources. This was the first study to apply strategic foresight to weed management planning in a realistic, culturally complex setting and our work provides an exemplar for the application of the strategic foresight framework and our tools to other contexts.