In Australia approximately 10,000 mosquito-borne virus infections occur annually, the majority of which are caused by alphaviruses such as Ross River virus and Barmah Forest virus, and less commonly by flaviviruses such as West Nile/Kunjin virus. Primarily transmitted by mosquitos from the Aedes and Culex genera, these viruses cause debilitating chronic arthritic and neurological illnesses respectively, and lack specific treatments and vaccines. Australia currently manages mosquito-borne virus outbreaks through surveillance systems, pesticide and repellent deployments, reduction of available mosquito habitats, and behavioural avoidance of mosquitos. However, these approaches insufficiently control arbovirus transmission. Wolbachia is an endosymbiotic insect bacterium that is currently used to inhibit the transmission of other human pathogenic flaviviruses and alphaviruses, including dengue, Zika, and chikungunya by arthropod vectors such as the Aedes aegypti mosquito. Despite the success of this method, expansion of this strategy into other mosquito species to control additional arboviruses has been limited. Here, we utilised in vitro cell infection models and qPCR to demonstrate that Wolbachia strain wMel effectively inhibits replication of Australian endemic alphaviruses and flaviviruses in both Aedes albopictus-derived cells, and Culex quinquefasciatus-derived cells. To the best of our knowledge, our research represents not only the first introduction of wMel into a Culex quinquefasciatus model either in vitro or in vivo, but also the first assessment of the antiviral activity of a transinfected Wolbachia strain in a Culex quinquefasciatus model. Our data supports further research into the future utilisation of wMel as a biocontrol strategy to minimise the transmission of Australian endemic alphaviruses and flaviviruses spread by Culex and Aedes mosquitos.