‘Baekseung’, a new variety of Flammulina velutipes, was bred by mating two monokaryotic strains isolated from KMCC 4210 and KMCC 4216 in the Mushroom Research Division, Baekseung ARES in 2016. The Baekseung and Uri1ho strains showed fast mycelial growth and mycelial density on malt extract agar media after 7 days of incubation. The spawn running period on the sawdust substrate required a cultivation period and temperature of 30 days and 25oC, respectively, for primordia formation where in fruiting body development occurred from 11±1 days at 14oC and 14±1 days at 7oC. The length of the pilei and stipes of the Baekseung harvested in optimal stag were 11.3±0.4 and 89.2±7.1 mm, respectively, whereas the values for Uri1ho were 10.7±1.0 and 91.3±20.8 mm, respectively. The yield of the Baekseung and Uri1ho strain grown on the sawdust substrate was 153.7±12.5 and 139.8±17.8 g, respectively, per 850 ml in bottle cultivation. The inferred tree exhibited a phylogenetic relationship between the Korean white fruiting body strains of Baekseung, Uri1ho and Fv-14-a-38, Fv-14-a-51, and the Japanese white fruiting body-forming strains of KMCC 4226, and these were confirmed to be genetically related.