Plants have a diverse array of secondary metabolites as part of their defense mechanism against various stress conditions. These secondary metabolites are broadly classified into phenolics, alkaloids, and terpenes. Ultraviolet-B (UV-B) radiation is one such environmental factor that acts both as a stressor and regulator for plants. UV-B mediated responses of plants including regulation of secondary metabolites biosynthesis involve two pathways, i.e., UVR8 (UV resistance locus 8) mediated UV-B specific and non-specific pathways. By involving these two pathways UV-B regulate the biosynthesis of secondary metabolites at the transcriptional level. UV-B radiation affects the expression of numerous genes of the enzymes involved in the production of secondary metabolites that may ultimately affect the accretion of secondary metabolites in plants. However, these responses to UV-B vary depending on species, cultivars, UV-B dose, developmental stage of plants, experimental conditions, and existing environmental factors. Therefore, a thorough investigation of the effects of UV-B on gene expression and biosynthesis of secondary metabolites in plants is covered in the present review.