Islands are biodiversity hotspots, supporting a high proportion of endemic plant and animal species, yet they face disproportionately high extinction rates due to the introduction of invasive alien species. Globalization has intensified these risks, as islands increasingly rely on shipping and air transport for supplies, and tourism for economic growth, heightening the likelihood of alien species introductions. Biosecurity management plans are established tools for preventing the introduction of invasive alien species to islands, yet only a small fraction of islands globally have such plans. A focus of these plans should be mitigating introductions through human activities, which are the primary pathways associated with invasive alien species introductions onto islands. Mitigating measures for intentional human introductions are generally easier to manage than unintentional ones, however, there remain significant social challenges associated with both pathways. A future challenge in island biosecurity will be sustaining investment in preventative measures, with international collaboration likely to play a key role in success.