Naturally producedhalogenatedcompounds are ubiquitous across all domains of life where they perform a multitude of biological functions and adopt a diversity of chemical structures. Accordingly, a diverse collection of enzyme catalysts to install and removehalogensfrom organic scaffolds has evolved in nature. Accounting for the different chemical properties of the fourhalogenatoms (fluorine, chlorine, bromine, and iodine) and the diversity and chemical reactivity of their organic substrates, enzymes performing biosynthetic and degradativehalogenationchemistry utilize numerous mechanistic strategies involving oxidation, reduction, and substitution. Biosynthetichalogenationreactionsrange from simple aromatic substitutions to stereoselective C-H functionalizations on remote carbon centers and can initiate the formation of simple to complex ring structures. Dehalogenating enzymes, on the other hand, are best known for removinghalogenatoms from man-made organohalogens, yet also function naturally, albeit rarely, in metabolic pathways. This review details the scope and mechanism of nature'shalogenationand dehalogenation enzymatic strategies, highlights gaps in our understanding, and posits where new advances in the field might arise in the near future.