Ornamental foliage plants have long been cultivated for their attractive leaves. Variation in leaf traits of ornamental foliage plants is one of the goals in breeding. MYB transcription factors regulate many aspects of leaf development, and thus influence morphological traits of leaves. However, little is known about the function of MYB transcription factors in leaf development ofCymbidium, one of the most economically important ornamental plants in the world. In the present study, a MYB transcription factor, CcMYB24, was identified and the corresponding gene cloned from a new orchid mutant, TRIR-2, which produces more leaves than control plants. The CcMYB24 showed a higher expression level in ‘TRIR-2’ than in control plants, and the protein was located in the nucleus. The sequence ofCcMYB24showed a high similarity withRAX2-likegenes which belong to theR2R3-MYBgene family in otherCymbidiumplants. Overexpression ofCcMYB24resulted in a phenotype with an increased number of leaves, elevated chlorophyll content, and decreased contents of carotenoids and flavonoids inArabidopsis. These results provide functional evidence for the role ofCcMYB24in promoting the production of leaves in ‘TRIR-2’. Understanding the role ofCcMYB24inCymbidiumwill be beneficial for the molecular breeding of ornamental foliage plants.