In the present study, a dynamic global subgrid-scale eddy diffusivity model for large eddy simulation of scalar transport in complex turbulent flows is proposed by generalizing the dynamic global subgrid-scale eddy viscosity model [Phys. Fluids, 18 125109 (2006) and Phys. Fluids, 22 075106 (2010)]. The global model coefficient in the subgrid-scale model is determined by a dynamic procedure based on the Germano identity such that the model coefficient is globally constant in space but varies only in time. Large eddy simulations of passive scalar transport in turbulent channel flow, turbulent boundary layer, and turbulent ribbed channel flow are conducted and the proposed model shows an excellent performance for all the flows considered. Since the proposed model requires no ad hoc clipping and/or averaging over a homogeneous direction, it can be readily applied to large eddy simulation of scalar transport in complex turbulent flows.