There is building consensus that nonstate actors have the potential to drive more ambitious action toward climate targets than governments, thus driving the necessary transition to ensure that humanity remains within a safe operating space. These bottom-up mitigation activities, however, require individual targets on both direct and indirect (upstream) greenhouse gas (GHG) emissions in order to reconcile trade-offs between global and local sustainability goals. Here we use a scenario-driven approach based on a global multiregional input-output (GMRIO) model to develop scope 3 emission reduction targets for individual economic sectors, comparable across countries and geographies. Under an ambitious carbon mitigation scenario for 2035 (that follows a trajectory of 1.75 °C total warming by 2100), global upstream scope 3 emission intensities need to be reduced by an additional 54% compared to a baseline scenario with reference technology. On a sectoral basis, this is equivalent to a 58-67% reduction in energy, transport, and materials, a 50-52% reduction in manufacturing, services, and buildings, and a 39% reduction in agriculture, forestry, and other land use. By aligning indirect supply chain targets with ambitious carbon mitigation scenarios, our approach can be used by nonstate actors to set actionable scope 3 targets and to build climate-compatible business models.