A one-pot synthesis of vicinal diamines using indoles, pyrazoles, and phenothiazines in a tandem multi-component reaction is developed. The utilization of a copper-iodine co-catalytic system enables the generation of a diverse range of vicinal diaminoindoles with good selectivity and moderate to good yields. An attractive aspect of this method is that it can be conducted under mild and environmentally friendly conditions, showcasing its potential as an alternative approach for synthesizing vicinal diamines. Moreover, the use of a multicomponent tandem reaction highlights the power and versatility of such strategies in synthetic chemistry.