A radiolabeled amino acid O-[18F]fluoromethyl-D-tyrosine (D-[18F]FMT) has been reported to show high tumor uptake. However, introduction of [18F]fluoromethyl group was difficult and was an issue to be solved. We solved it by using a precursor containing 1,2,3-triazolium salt. D-[18F]FMT was synthesized from (R)−1-((4-(2-((tert-butoxycarbonyl)amino)−3-((3,4-dimethylbenzyl)oxy)−3-oxopropyl)phenoxy)methyl)−3-methyl-4-phenyl-1H−1,2,3-triazol-3-ium trifluoromethanesulfonate via intra-molecular 18F-fluorination and subsequent removal of the protecting groups. The total synthesis time was 65min (including purification) and the overall radiochemical yield was 9% based on the isolated product (not decay-corrected). The resulting D-[18F]FMT was obtained with high radiochemical purity (> 99%) and specific activity (100–150 GBq/μmol). D-[18F]FMT also achieved excellent results in pharmacological evaluation such as stability test and protein binding assay. We expect that this simple one-pot labeling method would help using D-[18F]FMT more widely.