The fight against mosquito-borne diseases in sub-Saharan Africa is significantly hindered by the absence of comprehensive, long-term, and high-quality datasets. This limitation hinders our understanding of disease transmission dynamics, the effects of climate change, the consequences of anthropogenic factors such as deforestation and urbanization, and the impacts of vector control interventions. Although the WHO advocates for surveillance as a core intervention against vector-borne diseases, most low-income countries lack the financial and technical capacity to implement this on a large scale. Furthermore, there are no systematic efforts to collect such critical data in Africa, even as risks from climate and land use changes increase. We therefore propose to establish a networked observatory for systematic and long-term collection, analysis and dissemination of high-quality data on mosquitoes and mosquito-borne diseases in Africa, starting with five countries in the east & southern Africa region. The observatory will comprise geographically dispersed data collection nodes, reflecting spatial variations in climate, disease epidemiology, and socio-economic conditions, and will be owned and managed locally by African partners to enhance sustainability. To maximize value, the observatory will cover multiple mosquito-borne diseases, collecting standardized data on entomological metrics such as vector densities, species diversity, seasonal phenology, host preferences, transmitted pathogens, and genomic variations, alongside critical climatic, anthropogenic, and other environmental factors. We will build in-country capacity to perform all the entomological and genomic assays locally without having to ship samples abroad; including capacity to analyze, interpret and use the data. We will also gather summaries of health metrics from local facilities and collaborate with partners to include One Health indicators, aligning with global health security priorities.