1,3‐Diamines are an important class of compounds that are broadly found in natural products and are also widely used as building blocks in organic synthesis. Although the intramolecular C−H amination of N‐alkylsulfamide derivatives is a reliable method for the construction of 1,3‐diamine structures, the majority of these methods involve the use of a transition‐metal catalyst. We herein report on a new transition‐metal‐free method using tert‐butyl hypoiodite (t‐BuOI) or N‐iodosuccinimide (NIS), enabling secondary non‐benzylic and tertiary C−H amination reactions to proceed. The cyclic sulfamide products can be easily transformed into 1,3‐diamines. Mechanistic investigations revealed that amination reactions using t‐BuOI or NIS each proceed via different pathways.