Peroxisomes perform important metabolic functions, including lipid metabolism. This study finds that human cytomegalovirus (HCMV) and herpes simplex virus 1 (HSV1) induce peroxisome biogenesis and changes to peroxisome morphology that support viral infection. Using proteomics, the authors observed a global increase in the abundance of peroxisomal proteins during HCMV and HSV1 infections. Microscopy analysis and mathematical modelling showed that infection caused peroxisome growth and fission, leading to an increase in the number of peroxisomes. On average, peroxisomes became larger in size and more elongated, which causes an increase in the peroxisome membrane-to-lumen ratio. HCMV-induced peroxisome biogenesis also enhanced the synthesis of the phospholipid plasmalogen, increasing virus production. Altogether, this suggests that these viruses exploit peroxisome lipid metabolism to enhance viral replication.