Asparagopsis taxiformis is a red seaweed with significant potential as an antimethanogenic feed additive for ruminant livestock. Managing light intensity in A. taxiformis aquaculture is crucial for enhancing production of biomass and key halogenated natural products, specifically bromoform. However, a comprehensive understanding of the genes involved in bromoform biosynthesis is required to explore the interplay between light, growth and bromoform production to direct culture management. Bromoform is synthesised by vanadium bromoperoxidases (VBPOs), but the influence of specific VBPOs on bromoform production in A. taxiformis is unclear, as are the involvement of other genes. Here, we investigated the impact of light intensity on gene expression and bromoform concentration within the filamentous tetrasporophyte-stage of A. taxiformis. A. taxiformis (Lineage 6, Sunshine Coast, Australia) was cultured under four different light intensities for 14 days, in which 100 µmol photons m−2 s−1 had the greatest effect, doubling both growth rate and bromoform concentration compared to the control of 25 µmol photons m−2 s−1. A transcriptomic approach incorporating differential gene expression and enrichment analyses provided insights into gene interactions and function. We observed differential expression in genes essential for growth, energy metabolism and oxidative stress response, including photosynthesis-associated genes and other peroxidases. Three VBPO genes were characterised through comparative sequence and phylogenetic analyses, with two demonstrating significant downregulation in response to increasing light intensity. We discuss these results in the context of broader regulation of the VBPOs, and the potential involvement of other bromoform biosynthesis-associated genes in A. taxiformis.