The mechanism of visible light-driven Ni–C(aryl) bond homolysis in (2,2′-bipyridine)NiII(aryl)(halide) complexes, which play a crucial role in metallaphotoredox catalysis for cross-coupling reactions, has been well studied. Differently, the theoretical understanding of Ni–halide bond homolysis remains limited. In this study, we introduce a novel electronic structural framework to elucidate the mechanisms underlying photoinduced Ni–Br bond rupture in the (dtbbpy)NiII(aryl)(Br) complex. Using multireference ab initio calculations, we characterized the excited state potential energy surfaces corresponding to metal-to-ligand charge transfer (MLCT) and ligand-to-metal charge transfer (LMCT). Our calculations reveal that the Ni–Br dissociation, triggered by an external photocatalyst, begins with the promotion of Ni(II) to a 1MLCT excited state. This state undergoes intersystem crossing with repulsive triplet surfaces corresponding to the 3MLCT and Br-to-Ni 3LMCT states, resulting in Ni–Br bond breaking via the Dexter energy transfer mechanism. In the absence of a photocatalyst, the photoexcited Ni(II) favors Ni–C(aryl) homolysis, whereas the presence of a photocatalyst promotes Ni–Br dissociation. The Ni(III) species, resulting from the oxidation of Ni(II) by the photocatalyst, was found to be unproductive toward Ni–Br or Ni–C(aryl) activation.