Protected areas (PAs) are central to global efforts to prevent species extinctions, with many countries investing 27 heavily in their establishment. Yet, the designation of PAs alone can only abate certain threats to biodiversity. Targeted management within PAs is often required to achieve fully effective conservation within their boundary. It remains unclear what combination of PA designation and management is needed to remove the suite of processes that imperil species. Here, using Australia as a case study, we use a dataset on the pressures facing threatened species to determine the role of PAs and management in conserving imperilled species. We found that PAs that are not resourced for threat management could remove one or more threats to 1185 (76%) species and all threats very few (n=51, 3%) species. In contrast, a PA network that is adequately resourced to manage threatening processes within their boundary would remove one or more threats to almost all species (n=1551; ~100%) and all threats to almost half (n=740, 48%). However, 815 (52%) species face one or more threats that require coordinated conservation actions that PAs alone could not remove. This research shows that investing in the continued expansion of Australia’s PA network without providing adequate funding for threat management within and beyond the existing PA network will benefit very few threatened species. These findings highlight that as the international community expands the global PA network in accordance with the 2020 Strategic Plan for Biodiversity, a much greater emphasis on the effectiveness of threat management needed.