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The Suzuki-Miyaura cross-coupling of amides by selective N-C acyl bond cleavage represents a powerful tool for constructing biaryl ketones from historically inert amide bonds. These amide bond activation reactions hinge upon efficient oxidative addition of the N-C acyl bond to Pd(0). However, in contrast to the well-researched activation of aryl halides by C(sp)-X oxidative addition, very few studies on the mechanism of C(acyl)-N bond oxidative addition and catalyst effect have been reported. Herein, we report a study on [Pd(NHC)(sulfide)Cl] catalysts in amide N-C bond activation. These readily prepared, well-defined, air- and moisture-stable Pd(II)-NHC catalysts feature SMe (DMS = dimethylsulfide) or S(CHCH) (THT = tetrahydrothiophene) as ancillary ligands. The reaction development, kinetic studies, and reaction scope are presented. Extensive DFT studies were conducted to gain insight into the mechanism of C(acyl)-N bond oxidative addition and catalyst activation. We expect that [Pd(NHC)(sulfide)Cl] precatalysts featuring sulfides as well-defined, readily accessible ancillary ligands will find application in C(acyl)-X bond activation in organic synthesis and catalysis.