We report the first detection of Y280-lineage H9N2 avian influenza viruses in live bird markets in Korea during July 2020. The viruses were isolated from domestic ducks and chickens traded in three markets in two different provinces, indicating dispersal of the newly introduced viruses. Complete genome sequencing and comparative phylogenetic analyses of all eight gene segments of the viruses showed high nucleotide homology to a Y280-lineage H9N2 avian influenza virus isolated in a chicken farm in China, which belongs to one of the most prevalent H9N2 genotypes in China. Increasing human cases of the same genotype H9N2 infection in China and the mammalian specific markers present in the viruses isolated suggest potential implications for public health.