Recent evidence of increasing accumulation of micro- and nanoplastics (MnP) in soils and groundwater raise 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 intersectoral capacity for analysing the fate, transport and impacts of MnP in soils and groundwater to develop solutions for reducing their environmental and public health risks, 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 supra-disciplinary and inter-sectoral research and training network on solutions to the emerging crisis of MnP pollution in subsurface ecosystems in soils and groundwater, 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 individually funded through ETHZ [CH] and three funded through UoB, RU and Polymateria [UKRI] as Associated Partners) in environmental and social science, ecotoxicology, soil science and aquatic ecology, analytical chemistry, agronomy, data science and numerical modelling as well as responsible innovation, method standardization for use in regulatory decision making and risk assessment. The integrated training programme will prepare DCs with skill sets that are urgently required in agricultural, water, chemical, and manufacturing industries, environmental and regulatory agencies, academia, and the public sector and includes training provision by key stakeholders that will directly benefit from the training in this network.