The accumulation of mismanaged plastic waste (MPW) in the environment is a significant global concern. This study, using country-level data on waste management combined with high-resolution distributions and long-term projections of population and GDP, presents projections of global MPW generation at a resolution of ~1 km from now to 2060. It estimates that between 60 and 99 million metric tons (Mt) of MPW were produced globally in 2015. Under a business-as-usual scenario, this figure could triple to 155–265 Mt y−1 by 2060. The future MPW load will continue to be disproportionately high in African and Asian continents. However, this growth in plastic waste can be reduced if developing economies significantly invest in waste management infrastructures as their GDP grows, and if efforts are made internationally to reduce the fraction of plastic in municipal solid waste. Using the projections, it is demonstrated that the majority of MPW (91%) are transported via watersheds larger than 100 km², suggesting that rivers are major pathways for plastic litter to the ocean. The study highlights the urgency of addressing the issue and emphasizes the need for international cooperation and policy changes to mitigate the environmental impact of plastic waste.The accumulation of mismanaged plastic waste (MPW) in the environment is a significant global concern. This study, using country-level data on waste management combined with high-resolution distributions and long-term projections of population and GDP, presents projections of global MPW generation at a resolution of ~1 km from now to 2060. It estimates that between 60 and 99 million metric tons (Mt) of MPW were produced globally in 2015. Under a business-as-usual scenario, this figure could triple to 155–265 Mt y−1 by 2060. The future MPW load will continue to be disproportionately high in African and Asian continents. However, this growth in plastic waste can be reduced if developing economies significantly invest in waste management infrastructures as their GDP grows, and if efforts are made internationally to reduce the fraction of plastic in municipal solid waste. Using the projections, it is demonstrated that the majority of MPW (91%) are transported via watersheds larger than 100 km², suggesting that rivers are major pathways for plastic litter to the ocean. The study highlights the urgency of addressing the issue and emphasizes the need for international cooperation and policy changes to mitigate the environmental impact of plastic waste.