A new distinct cultivar of Aster plant named ‘DASDEBI’, characterized by its upright and inverted conical plant habit; yellow-green and gray-green foliage; decorative, composite-type inflorescence with about 250 to 300 violet-blue-colored ray florets; and only about 10 to 20 disc florets per inflorescence which are white in color with yellow-orange tips (almost 100% filled capitulae).