A new and distinct cultivar of Chrysanthemum plant named `Sunny Yoolympia`, characterized by its uniform and outwardly spreading plant habit; strong and freely branching growth habit; dark green-colored foliage; uniform flowering response and habit; typically grown as a disbud-type; early flowering habit; large decorative-type inflorescences with elongated oblong-shaped ray florets; light yellow-colored ray florets; and excellent postproduction longevity with plants maintaining good substance and color for about four to five weeks in an interior environment.