The mechanism of a trinuclear cooperative dehydrogenative C−N bond‐forming reaction is investigated in this work, which avoids the use of chelate‐assisting directing groups. Two new highly efficient Ru/Cu co‐catalyzed systems were identified, allowing orders of magnitude greater TOFs than the previous state of the art. In‐depth kinetic studies were performed in combination with advanced DFT calculations, which reveal a decisive rate‐determining trinuclear Ru–Cu cooperative reductive elimination step (CRE).