Sustainable Development Goals (SDGs) call for implementing sustainable practices by 2030, but their effects on microplastic pollution over time are limited. Here, we aimed to understand better the effects of improved centralized‐sanitation and reduced production and consumption on point‐source inputs of microplastics into rivers from 2010 to 2100 with a 10‐year time step for 10,226 sub‐basins globally. We developed scenarios with sustainable practices and implemented them into the MARINA‐Plastics model. Our baseline scenario followed the “middle‐of‐the‐road” socioeconomic pathway, where global microplastics (MIPs) in rivers will almost triple by 2100. European and Asian rivers were major MIP pollution hotspots in the past whereas Africa will join them in the future. Better centralized‐sanitation may reduce MIPs in rivers globally in the long‐term by 2100, while controlled waste generation may reduce MIPs in rivers in the short‐term by 2030. Our insights could guide policymaking in implementing SDG 6 and 12. We argue that combined sustainable practices could reduce MIP in global rivers in the short‐ and long‐term.