Structurally robust tetradentate gold(III)‐emitters have potent material applications but are rare and unprecedented for those displaying thermally activated delayed fluorescence (TADF). Herein, a novel synthetic route leading to the preparation of highly emissive, charge‐neutral tetradentate C^C^N^C gold(III) complexes with 5‐5‐6‐membered chelate rings has been developed through microwave‐assisted C−H bond activation. These complexes show high thermal stability and with emission origin (3IL, 3ILCT, and TADF) tuned by varying the substituents of the C^C^N^C ligand. With phenoxazine/diphenylamine substituent, we prepared the first tetradentate gold(III) complexes that are TADF emitters with emission quantum yields of up to 94 % and emission lifetimes of down to 0.62 μs in deoxygenated toluene. These tetradentate AuIII TADF emitters showed good performance in vacuum‐deposited OLEDs with maximum EQEs of up to 25 % and LT95 of up to 5280 h at 100 cd m−2. Gold(III) complexes supported by tetradentate ligands for OLEDs can be prepared under microwave conditions. Depending on the ligand substituents, these complexes exhibit short‐lived thermally activated delayed fluorescence (TADF) with quantum yields of up to 0.94.