Background A large share of the world’s population lives in low elevation coastal areas, which are vulnerable to freshwater salinisation resulting from sea level rise. These changes in the environmental conditions affect local aquatic ecology, including disease vectors and their predators. We studied how projected changes in salinisation affect freshwater mosquitoes’ life-history traits, their predators and their ability to transmit viruses. Methods We experimentally investigated the effects of salinity on larval survival and development, as well as the longevity, size, and Sindbis virus vector competence of adult Culex pipiens mosquitoes. In addition, salt tolerance of invertebrate predators of mosquito larvae was assessed by analysing a long-term dataset with field observations from a range of fresh to extremely salty habitats in the Netherlands. Results Larvae survived up to ~45% ocean water salinity (9 g/l Cl⁻), though life-history traits were only affected at near-lethal salinity. Even at 8 g/l Cl⁻, effects were quite minimal: larvae exhibited higher mortality (24%), delayed development (17%), and adults were marginally smaller (5.5%), but lived thrice longer with unchanged vector competence. Across the same salinity gradient, predator diversity decreased markedly, losing approximately 90% of dragonflies and aquatic beetles, and 65% of aquatic bugs. Conclusion Limited effects of increasing salinity on mosquito survival combined with substantially impoverished predator communities (i.e. ecological release) potentially result in a rise in mosquito abundances in salinising coastal areas. This highlights that, besides changes in temperature and precipitation, salinisation may become a critical factor influencing mosquito-borne disease risk in coastal landscapes.