A proof-of-concept for the one-step, synthetically challenging cyclic and acyclic perfluoroalkylation of (hetero)arenes driven by the valence change of a vitamin B₁₂ derivative as a cobalt catalyst in the presence of fluoroalkylating reagents (X(CF₂)₄X) is presented. The consecutive formation of cobalt–carbon bonds and generation of fluoroalkyl radicals by homolysis are the key steps for the reaction to proceed.