AquaBioSens aims to drive the decentralisation of tools for the measurement of aquatic hazards and pollution. We will produce and demonstrate new handheld devices to measure contaminants of emerging concern, microbial biohazards and heavy metals. The aim is to make monitoring more efficient and widely accessible, supporting the EU Mission to “Restore our ocean and waters by 2030” Mission, and specifically the Destination “Clean Environment and Zero Pollution”, as well the Water Framework Directive and Marine Strategy Framework Directive. We will achieve this by developing novel analytics based on cutting-edge techniques: i) immunoassays to measure organic contaminants, ii) isothermal environmental RNA quantification for harmful microalgae and fecal coliform bacteria, and iii) two novel whole cell biosensors based on genetically modified diatom microalgae and fish gill epithelia for multiplexed heavy metals quantification and toxicity assessment. These will be coupled with state-of-the art sensors such as acoustic biosensors, multichannel fluorimetry and organ-on-chip microfluidic devices. Low-cost fabrication strategies will ensure that the developed technologies are accessible to end-users, such as industry operators and government inspection agencies responsible for environmental monitoring. New digital real-time data feeds will enable seamless data flows from sensors to the web, including a dedicated live dashboard. The prototype devices will be demonstrated and validated in potentially polluted coastal and freshwater environments in the UK, Ireland and Greece, with the support of local government inspection agencies. Together with measures to disseminate results widely to the international community, stakeholders and citizen science groups, we will maximize exploitation with a view to commercialize the new technologies in future.