Vitamin D has a well-known critical role in calcium and bone homeostasis. In recent years, there has been an increased interest in the potential regulatory role of vitamin D on metabolic pathways implicated in muscle functions. Evidence coming from epidemiologic studies has demonstrated that poor vitamin D status is associated with worse muscle functions. However, whether vitamin D deficiency and supplementation has a role on sarcopenia is not fully known. This review will focus on current knowledge and emerging data regarding the role of vitamin D in muscle functions and sarcopenia.