Buddleja curviflora is a deciduous shrub native to southern Japan and Taiwan, where it grows in thickets on stony slopes at elevations of 100–300 m. B. curviflora was named and described Hooker & Arnott in 1838. Plants in Taiwan have been described as a separate species Buddleja formosana and assessed as Critically Endangered by IUCN, but the distinction is not recognized by Li and Leeuwenberg, who sank formosana as a synonym.