Site-selective vanadium-dependent haloperoxidases (VHPOs) are a unique enzyme family that catalyze selective halogenation reactions previously characterized within bacterial natural product biosynthetic pathways. However, the broader chemical roles and biological distribution of these halogenases remains to be explored. Using bioinformatic methods, we have defined a VHPO subfamily that regioselectively brominates alkyl quinolone (AQ) quorum sensing molecules. In vitro AQ halogenation activity was demonstrated from phylogenetically distinct bacteria lacking established AQ biosynthetic pathways and sourced from diverse environments. AQ-VHPOs show high sequence and biochemical similarities with negligible genomic synteny or biosynthetic gene cluster co-localization. Exposure of VHPO-containing microbes to synthetic AQs or established bacterial producers identifies the chemical and spatial response to subvert their bacteriostatic effects. The characterization of novel homologs from bacterial taxa without previously demonstrated vanadium enzymology suggests VHPO-mediated AQ bromination is a niche to manipulate the chemical ecology of microbial communities.