Catalyzes the transfer of L-fucose, from a guanosine diphosphate-beta-L-fucose, to the N-acetyl glucosamine (GlcNAc) of a distal lactosamine unit of a glycoprotein or a glycolipid-linked polylactosamine chains through an alpha-1,3 glycosidic linkage and participates in particular to the Lewis x (Lex)/CD15 epitope biosynthesis in neurons which allows cell differentiation, cell adhesion, and initiation of neurite outgrowth (PubMed:12626397, PubMed:9756916, PubMed:15121843, PubMed:16973732). Also fucosylates di-, tri- and tetraantennary N-glycans linked to glycoproteins and the inner lactosamine unit of the alpha2,3-sialylated polylactosamine resulting in sLex (CD15s) epitope synthesis (By similarity). Furthermore, it is capable of synthesizing Lewis a (Lea), although to a lesser extent than Lex and Lewis y (Ley) and to confer SELE-dependent, but not SELL- and SELP-selectin-dependent, cell rolling and adhesion by enhancing Lex and sLex synthesis (By similarity). May also fucosylate the internal LacNAc unit of the polylactosamine chain to form VIM-2 antigen that serves as recognition epitope for SELE. a beta-D-galactosyl-(1->4)-N-acetyl-beta-D-glucosaminyl derivative + GDP-beta-L-fucose = a beta-D-galactosyl-(1->4)-[alpha-L-fucosyl-(1->3)]-N-acetyl-beta-D-glucosaminyl derivative + GDP + H(+) an alpha-Neu5Ac-(2->3)-beta-D-Gal-(1->4)-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-beta-D-GlcNAc derivative + GDP-beta-L-fucose = an alpha-Neu5Ac-(2->3)-beta-D-Gal-(1->4)-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-[alpha-L-Fuc-(1->3)]-beta-D-GlcNAc derivative + GDP + H(+) alpha-N-glycoloylneuraminosyl-(2->3)-beta-D-galactosyl-(1->4)-N-acetyl-beta-D-glucosaminyl-(1->3)-beta-D-galactosyl-(1->4)-N-acetyl-beta-D-glucosaminyl-(1->3)-beta-D-galactosyl-(1->4)-beta-D-glucosyl-(1<->1')-ceramide + GDP-beta-L-fucose = alpha-N-glycoloylneuraminosyl-(2->3)-beta-D-galactosyl-(1->4)-N-acetyl-beta-D-glucosaminyl-(1->3)-beta-D-galactosyl-(1->4)-[alpha-L-fucosyl-(1->3)]-N-acetyl-beta-D-glucosaminyl-(1->3)-beta-D-galactosyl-(1->4)-beta-D-glucosyl-(1<->1')-ceramide + GDP + H(+) alpha-D-galactosyl-(1->3)-beta-D-galactosyl-(1->4)-N-acetyl-beta-D-glucosaminyl-(1->3)-beta-D-galactosyl-(1->4)-beta-D-glucosyl-(1<->1')-ceramide + GDP-beta-L-fucose = a neolactoside IV(3)-alpha-Gal,III(3)-alpha-Fuc-nLc4Cer + GDP + H(+) a neolactoside nLc4Cer + GDP-beta-L-fucose = a neolactoside III(3)-alpha-Fuc-nLc4Cer + GDP + H(+) Activated by Mn2+. Protein modification; protein glycosylation. Mainly detected in brain and kidney. Expressed in 1-cell embryos and then decreased dramatically in 2- and 4-cell embryos. It increases transiently in 8-cell embryos and then vanishes completely at the morula stage (PubMed:15121843). Predominantly expressed at all stages both in cerebrum and in cerebellum containing mesencephalon. Expression increases during the embryonic stage with the highest expression at P0 and decreases. Expression increases from the embryo to P7 stage, with the highest expression at P7, and decreases in adult brain. At P7 expressed in the neurons in layers II-IV and those in layers V and VI of the cerebral cortex. At P7 expressed in cerebellum, granule neurons in the internal granule cell layer (PubMed:12626397). N-glycosylated with complex-type N-glycans. Homozygous Fut9 knockout mice develop normally, with no gross phenotypic abnormalities, and are fertile. Belongs to the glycosyltransferase 10 family. Fucosyltransferase 9