A new and distinct cultivar of Chrysanthemum plant named `Yomary`, characterized by its compact, upright and outwardly spreading plant habit; freely branching habit; dense and full growth habit; uniform and freely flowering habit; decorative-type inflorescences with elongated oblong to ligulate-shaped ray florets; rich yellow-colored ray florets; and natural season flowering about September 30.sup.th in the Northern Hemisphere.