In enzymology, a flavonol-3-O-glucoside L-rhamnosyltransferase () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are UDP-L-rhamnose and flavonol 3-O-D-glucoside, whereas its two products are UDP and flavonol 3-O-[beta-L-rhamnosyl-(1->6)-beta-D-glucoside].
This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is UDP-L-rhamnose:flavonol-3-O-D-glucoside 6<nowiki></nowiki>-O-L-rhamnosyltransferase. Other names in common use include uridine diphosphorhamnose-flavonol 3-O-glucoside, rhamnosyltransferase, and UDP-rhamnose:flavonol 3-O-glucoside rhamnosyltransferase. This enzyme participates in flavonoid biosynthesis.