The aim of this research was to determine the effect of development and UV‐B on flavonols and the regulation of gene activity in Vitis vinifera L. var. Sauvignon blanc grapes. Particular emphasis was placed on gene activity associated with the low and high fluence UV‐B responses. Flavonols, particularly quercetin and kaempferol glycosides, increased substantially upon fruit exposure due to UV‐B, with spatial analysis locating the changes to the berry skin. Of five VvFLS genes in grapes, two (VvFLS4 and 5) were found to be transcriptionally active, with VvFLS4 also being responsive to UV‐B but VvFLS5 was not. Of the transcription factors known to regulate FLS (VvMYB12, VvMYCA1 and VvWDRs), only VvMYB12 was found to be responsive to UV‐B. A number of candidate genes associated with the low and high UV‐B fluence responses were also studied (VvUVR8, VvHY5, VvCOP1 and VvCHS; PR genes and VvMAPK3; respectively). The genes associated with the low fluence response exhibited transcriptional regulation in line with reports from other species, while the PR genes and VvMAPK3 only appeared to be responsive in a high UV‐B fluence environment. Together, these data supports the view flavonol biosynthesis in grape is stimulated predominantly through the low fluence UV‐B response pathway. This research investigates the effect of development and UV‐B on flavonols and the regulation of gene activity in Vitis vinifera L. var. Sauvignon blanc grapes. Results suggest flavonol biosynthesis and gene activity are stimulated by UV‐B and the low fluence UV‐B pathway is a major determinant of this response. There is also a strong influence of development on gene expression. This is the first research to analyse signal transduction associated with the recently discovered UV‐B photoreceptor UVR8 and makes a substantial contribution to understanding UV‐B responses in an important commercial species.