A distinct cultivar of Chrysanthemum plant named 'Yomusic', characterized by its upright plant habit; dark green-colored foliage; freely flowering habit; decorative-type inflorescences that are about 6.8 cm in diameter; attractive light purple-colored ray florets; response time about 67 days; strong peduncles; and good postproduction longevity with inflorescences and foliage maintaining good substance and color for about three weeks in an interior environment.