BACKGROUND: Intensive care unit acquired-weakness syndrome (ICUAWS) leaves several complications in functional movements of patients such as severe walking disability. OBJECTIVE: Assessment of functional outcomes of 1-month inspiratory muscle training (IMT) in elderly with ICUAWS and severe walking disability was our aim. The design, setting, participants, and intervention. This study is a randomized controlled trial. ICUAWS patients who complained of severe walking disability on the Modified Functional Ambulatory Category Test (MFACT) were randomly assigned into the IMT group or control group, n = 20 for each group. Both groups received the traditional physical therapy program. RESULTS: The results showed that the post-therapy between-group comparison of ICUAWS sufferers/groups' parameters showed a significant improvement toward the IMT group in six-minute walk test, inspiratory and expiratory muscle strength, forced vital capacity, time up and go test, 10-m walk test, forced expiratory volume in the first second, 30-s sit-to-stand test, partial pressure of arterial blood oxygen and carbon dioxide, MFACT, oxygen saturation of arterial blood, physical, and mental summary of short form 36. CONCLUSION: In conclusion, IMT improves functional outcomes in ICUAWS patients with walking disability. TRIAL REGISTRATION NUMBER: The clinical trial ID of this ICUAWS trial is NCT06210763.