The Bi3+ (N,C,N)-pincer complex Ar'BiCl2 (1) [Ar' = 2,6-(Me2NCH2)(2)C6H3], reacts with 2 equiv of KOC6H3Me2-2,6 and (KOC6H3Pr2)-Pr-i-2,6 by ionic metathesis to form the anticipated bis(aryloxide) complexes Ar'Bi-(OC6H3Me2-2,6)(2) (2) and Ar'Bi((OC6H3Pr2)-Pr-i-2,6)(2) (3), respectively. However, the analogous reaction with 2 equiv of (KOC6H3Bu2)-Bu-t-2,6 forms (HOC6H3Bu2)-Bu-t-2,6 and a dark-orange complex containing only one aryloxide-derived ligand bound via a Bi-C and not a Bi-O linkage. This complex is formulated as Ar'Bi((C6H2Bu2)-Bu-t-3,5-O-4) (4), a product of para C-H bond activation. Structural, spectroscopic, and DFT studies and a comparison with the protonated analogue [Ar'Bi((C6H2Bu2)-Bu-t-3,5-OH-4)][BPh4] (5), which was obtained by treatment of 4 with [HNEt3] [BPh4], suggest that 4 contains an oxyaryl dianion. Complex 4 represents a fully characterizable product of a bismuth-mediated C-H activation and rearrangement of the type postulated in catalytic SOHIO processes.