Herein, we report a Cu catalyst system for umpolung Chan-Lam amination, enabling the efficient synthesis of unsymmetrical diarylamines from arylboronic esters and aryl azides. This sustainable approach facilitates C-N bond formation even at 35 °C without any additional ligands using an easily accessible catalyst and substrates. Mechanistic and computational studies revealed the intermediacy of the Cu(II) species. This method provides a cost-effective route to diarylamines, and it was successfully applied to the gram-scale synthesis of a flufenamic acid derivative.