Yellowtail kingfish (Seriola lalandi) are one of Australia’s most valued recreational and commercial species, with a single genetic stock encompassing south-eastern Australia and New Zealand (NZ). Previous tracking research was largely restricted to coastal habitats due to the challenges of accessing offshore habitats and limitations of conventional tagging and acoustic telemetry. As such, there is limited knowledge about habitat use of the sexually mature kingfish population, and the degree of connectivity between offshore and coastal environments. We used pop-up satellite archival tags (MiniPAT, Wildlife Computers), to investigate the movement behaviour of mature-sized kingfish (n = 43) off south-eastern Australia and NZ. Kingfish were tracked for a total period of 3016 days (mean ± sd. = 70 ± 85 days) and travelled a total distance of 29,488 km (mean ± sd. = 719 ± 828 km). We found marked differences in behaviour between kingfish in coastal environments (56% data days) compared to offshore environments (44% data days) (e.g. Lord Howe Island), with the latter utilising deeper waters but staying within their preferred thermal habitat. Regular movements and connectivity between coastal and offshore environments, including directional movements to seamounts by mature-sized kingfish, is consistent with hypothetical spawning habitats around offshore features.