Objectives: Physical inactivity in hospitals is common and is associated with poor patient and clinical outcomes. This review was undertaken to identify and describe the effectiveness of interventions implemented at the ward or system level for improving physical activity and reducing functional decline in general medical inpatients. The secondary aim was to describe the effects on length of stay, discharge destination, falls, and hospital costs. Design: Umbrella review. Setting and Participants: Systematic reviews that evaluated ward- or system-level interventions aiming to improve physical activity or reduce functional decline in medical inpatients. Methods: PubMed, EMBASE, Cochrane Database, CINAHL, JBI, and Web of Science databases were searched for English-language reviews published between 2000 and 2023. AMSTAR 2 was used to assess methodologic quality. Two reviewers independently assessed eligibility and methodologic quality and completed data abstraction, with results presented as a narrative synthesis. Results: The search yielded 568 systematic reviews of which 12 met criteria, half of which were published since 2020. Reviews included 76 unique primary studies with 72,645 participants. Most reviews were of low quality. Interventions that focused on progressive mobilization likely increased physical activity participation, reduced functional decline, and improved discharge home. Multicomponent interventions that employed multiple strategies targeting a broader range of barriers likely improved functional decline and discharge home and may have been associated with shorter length of stay. No interventions were associated with increased frequency of falls. Few studies reported costs. Conclusions and Implications: Progressive mobilization interventions and multicomponent interventions appear to be effective for improving physical activity participation and reducing functional decline in medical inpatients. Further high-quality studies may help to determine the most important aspects of multicomponent interventions. Standardized terminology related to inpatient physical activity may help promote a shared understanding and purpose across professions.