This Article demonstrates a mild oxidatively induced C(sp(3))-H activation at a high-valent Ni center. In contrast with most C(sp(3))-H activation reactions at Ni-II, the transformation proceeds at room temperature and generates an isolable Ni-IV sigma-alkyl complex. Density functional theory studies show two plausible mechanisms for this C-H activation process involving triflate-assisted C-H cleavage at either a Ni-IV or a Ni-III intermediate. The former pathway is modestly favored over the latter (by similar to 3 kcal/mol). The Ni-IV sigma-alkyl product of C-H cleavage reacts with a variety of nucleophiles to form C(sp(3))-X bonds (X = halide, oxygen, nitrogen, sulfur, or carbon). These stoichiometric transformations can be coupled using N-fluoro-2,4,6-trimethylpyridinium triflate as a terminal oxidant in conjunction with chloride as a nucleophile to achieve a proof-of-principle Ni-II/IV-catalyzed C(sp(3))-H functionalization reaction.