Hydroxamic acids are metal‐chelating compounds that show important biological activity including anti‐tumor effects. We have recently engineered the transketolase from Geobacillus stearothermopilus (TKgst) to convert benzaldehyde as a non‐natural acceptor substrate. Realizing the structural and electronic similarity to nitrosobenzene, we studied the TK‐catalyzed conversion of nitrosoarenes to yield N‐arylated hydroxamic acids. Here we demonstrate that wild‐type and variants of this versatile TKgst enzyme indeed induce the rapid biocatalytic conversion of variously p‐, m‐ and o‐substituted nitrosoarenes to produce a variety of corresponding N‐aryl hydroxamic acids via creation of a carbon‐nitrogen instead of a carbon‐carbon bond. Further structural modifications can be introduced by varying the donor component, such as hydroxypyruvate or pyruvate.