Carbon-nitrogen (C-N) bond-forming cross-coupling reactions catalyzed by palladium-based catalysts, the socalled Buchwald-Hartwig aminations, have been widely employed for the synthesis of pharmaceuticals and aryl-amine-based organic materials in academic and industrial settings. However, in solution, these reactions usually require glove-box and Schlenk-line techniques, which greatly reduces their practical utility. Here, we report the development of operationally simple mechanochemical C-N cross-coupling reactions in the solid-state. Intensive investigations of various ball milling parameters revealed that the air-stable ligand tri(1-adamantyl)phosphine can be used to achieve solid-state coupling reactions between aryl halides and diarylamines with high efficiency. Notably, all experimental operations of the developed protocol can be carried out in air, thus providing a more convenient, industrially attractive, and sustainable alternative to conventional solution-based palladium-catalyzed C-N coupling reactions.