We report a class of Au(Ⅰ)-based multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters designed for deep blue emission [(PzIPr)AuOBO and (SIPr)AuOBO], which exhibited a substantially shortened delayed lifetime and a narrow full width at half maximum (FWHM=40 nm). Remarkably, dual emission from both TADF and phosphorescence was observed in these MR-TADF complexes. The photoluminescence quantum yield (PLQY) of the emitters reached up to 0.99, a result attributed to the Au(Ⅰ)-activated triplet radiative transfer pathway. Solution-processed organic light-emitting diode (OLED) devices fabricated with (PzIPr)AuOBO delivered deep blue emission with CIE coordinates of (0.15, 0.07) and a maximum external quantum efficiency (EQE) of 7.0%.