This study was conducted from May 2017 to October 2019 to investigate the relationships among the habitat variables and bird diversity on 65 specific islands in the east and southern coastal regions of South Korea. Habitat valuables on each island were divided by the area of the island from the digital topographic map, distance from land (including island and mainland), and land cover. The bird diversity index was affected by the area of islands and the proportion of land cover of forest, water, and grass. The area of habitat was related to the carrying capacity of species richness. Increasing the area of the island could be positively associated with bird diversity. Spatial diversity in habitat increases the habitat usage of birds, which have different behaviors in foraging and breeding. Thus, increasing the area and spatial diversity in habitat positively correlate with bird diversity. Our results may be valuable for the management and conservation of the bird communities on specific islands in South Korea.