Older patients face increasing challenges in preserving mobility during hospitalization. This retrospective cohort study aimed to evaluate the effect of an Occupational Therapy (OT) program on mobility at discharge in older patients admitted to an Acute Geriatric Unit (AGU). All patients aged ≥65 years consecutively admitted to the AGU in an 18-month period were included in the study if scoring <4 or ≥ 8 at the Clinical Frailty Scale. Overall, 807 patients (median age 85 years, 50.2% females) were included: 665 (82%) received OT, while 142 who did not receive OT were used as controls. The Cumulated Ambulation Scale (CAS) was used to assess mobility at discharge. By multivariable logistic regression, OT was independently associated with higher odds of achieving higher CAS score at discharge. These findings emphasize the potential benefits of OT in acute geriatric settings, providing valuable insights for preserving mobility of frail older individuals during hospitalization.