The reported prevalence of sarcopenia has shown a wide range, crucially based on the diagnostic criteria and setting. This cross-sectional study evaluated the prevalence of sarcopenia and sought to identify factors associated with sarcopenia on admission in a specialized geriatric rehabilitation setting based on the newly developed the Asian Working Group for Sarcopenia algorithm. Among 87 participants (mean age, 76.05 ± 7.57 years), 35 (40.2%) were classified as showing sarcopenia on admission. Prevalence was high, particularly among participants ≥80 years old, with tendencies toward lower body mass index, smoking habit, lower cognitive function, and greater functional impairment compared with the non-sarcopenic group. Identification of sarcopenia in elderly patients before rehabilitation and consideration of risk factors may prove helpful in achieving rehabilitation outcomes.