Organohalogen compounds are essential in modern chemistry, serving as key structural motifs in pharmaceuticals, agrochemicals, and advanced materials (Zhang et al., 2025; Nguyen et al., 2024; Hicks et al., 2024; Lehmann et al., 2018; Ankade et al., 2021). Their unique reactivity, especially the ease of carbon-halogen bond transformations, underpins widespread applications such as transition-metal-catalyzed cross-coupling reactions (Festa et al., 2023; Cheng and Mankad, 2022; Ji et al., 2023; Iwai and Nishiwaki, 2024; Wei et al., 2023). In 2023, over 80 of the top 200 best-selling small-molecule drugs were halogenated (Williams et al., 2023), and since 2010, 96 % of newly launched pesticides have contained halogen atoms (Jeschke, 2017). Halogenation often imparts “magic effects” to lead compounds, enhancing potency, metabolic stability, and bioavailability, sometimes by orders of magnitude (Wang et al., 2024a, Wang et al., 2024b; Curtin et al., 2012; Chong et al., 2012). As demand for halogenated scaffolds continues to rise, efficient and selective halogenation strategies remain central to innovation in organic synthesis and drug development (Bradley et al., 2023; Wang et al., 2024a, Wang et al., 2024b).

While conventional chemical halogenation routes are widely used (Elfert et al., 2024; Wu et al., 2025; Shibatomi, 2023; Md. Din et al., 2024; Terrosu et al., 2025), biocatalytic strategies have gained attention for their regio- and stereoselectivity under mild conditions. Among halogenating enzymes, flavin-dependent halogenases, α-ketoglutarate-dependent halogenases, S-adenosyl-L-methionine (SAM) fluorinases, and haloperoxidases represent the most studied classes (Hegarty et al., 2023; Latham et al., 2018; Hu et al., 2025). Halohydrin dehalogenases also catalyze reversible conversions between halohydrins and epoxides, though limited by unfavorable equilibria and narrow substrate scope (Li et al., 2024; Hua et al., 2025).

Flavin-dependent halogenases enable highly selective halogenation of aromatics using O2 and flavin cofactors via a protein-bound hypohalous acid equivalent; however, they suffer from low activity and cofactor recycling issues (Hu et al., 2025; Lewis, 2024; Dai et al., 2024; Jiang et al., 2024). α-Ketoglutarate-dependent halogenases oxidatively halogenate unactivated CH bonds via iron-oxo intermediates, though often require carrier-protein-tethered substrates and show limited robustness (Gomez et al., 2023; Kastner et al., 2023; Papadopoulou et al., 2023; Chiang et al., 2025; Voss et al., 2020). SAM fluorinases are rare enzymes catalyzing nucleophilic CF bond formation under aqueous conditions, but remain constrained by narrow substrate scope and low abundance in nature (Sooklal et al., 2020; He et al., 2025; Feng et al., 2022; Zhao et al., 2024a, Zhao et al., 2024b; Lin et al., 2024).

Haloperoxidases, in contrast, activate halides (Cl−, Br−, I−) via hydrogen peroxide to produce electrophilic hypohalous acids (HOX), enabling diverse halogenation reactions (Höfler et al., 2019; Butler and Sandy, 2009; Agarwal et al., 2017; Chen, 2022). These are divided into heme- and vanadium-dependent classes (Zhao et al., 2024a, Zhao et al., 2024b; Hofrichter and Ullrich, 2006; Sharma et al., 2024, Sharma et al., 2025a, Sharma et al., 2025b; Hartung, 2025). While heme-dependent haloperoxidases such as those from Leptoxyphium fumago offer high activity, they are vulnerable to oxidative damage (Zhao et al., 2024a, Zhao et al., 2024b; Hofrichter and Ullrich, 2006). Vanadium-dependent haloperoxidases (VHPOs), on the other hand, exhibit exceptional tolerance to H2O2, high temperatures, and organic solvents, making them highly attractive for synthetic applications (Höfler et al., 2019; Wever et al., 2018).

Despite their promise, VHPOs remain under-reviewed (Höfler et al., 2019; Wever et al., 2018). Recent years have seen major advances in VHPO discovery (Kaneko et al., 2023; Cochereau et al., 2023; Zhang et al., 2024), mechanistic elucidation (Mitchell et al., 2024; Gérard et al., 2023; Zeides et al., 2025), expansion of catalytic reactions (Sharma et al., 2025a; Sharma et al., 2024; Baumgartner and McKinnie, 2024; Fu et al., 2025), and development of chemoenzymatic cascades (Zhao et al., 2025a, Zhao et al., 2025b; De Marchi et al., 2024). This review therefore aims at providing a comprehensive and critical evaluation of these developments, focusing on the synthetic utility, mechanistic insights, and emerging applications of VHPOs in modern biocatalysis.