Recent evidence of increasing accumulation of micro- and nanoplastics (MnP) in soils and groundwater raises severe concerns by agricultural and water industries, food manufacturers, regulators, environmental interest groups and citizens. Private and public sectors require detailed understanding of environmental and public health risks posed by MnP in soils and groundwater. The PlasticUnderground Doctoral Network creates supra-disciplinary, inter-sectoral capacity for analyzing the fate, transport and impacts of MnP in soils and groundwater, to develop solutions for reducing their environmental and public health risks, and for supporting the EC’s circular plastic economy strategy. The central aim of the PlasticUnderground Doctoral Network is to deliver international scientific excellence through a holistic research and training network aimed at providing solutions to the emerging crisis of MnP pollution in subsurface ecosystems, by integrating knowledge across traditional discipline boundaries to benefit the public and private sectors. The supra-disciplinary research programme includes unique training opportunities for a cohort of 10 Doctoral Candidates (DCs), plus one funded through ETHZ (CH) and three funded through UoB, RU and Polymateria (UK) in environmental and social sciences, ecotoxicology, soil science and aquatic ecology, analytical chemistry, agronomy, data science and numerical modelling as well as responsible innovation and standardization for use in regulatory decision making and risk assessment. The integrated training programme will prepare the DCs with skills that are urgently required in agricultural, water, chemical, and manufacturing industries, environmental and regulatory agencies, academia, and the public sector. The program also includes training provisions by key stakeholders that will directly benefit from the training within the Network.