Herein, we report a polar-radical relay strategy for alpha-C-H amination of cyclic amines with N-chloro-N-sodio-carbamates. The relay is initiated by in situ generation of cyclic iminium intermediate using N-iodosuccinimide (NIS) oxidant as an initiator, which then operates through a series of polar (addition and elimination) and radical (homolysis, hydrogen- and halogen atom transfer) reactions to enable the challenging C-N bond formation in a controlled manner. A broad range of alpha-amino cyclic amines were readily accessed with excellent regioselectivity, and the superb applicability was further demonstrated by functionalization of biologically relevant compounds.