Older adults often experience functional decline following acute medical care. This functional decline may lead to permanent disability, which will increase the burden on the medical and long-term care systems, families, and society as a whole. Post-acute care aims to promote the functional recovery of older adults, prevent unnecessary hospital readmission, and avoid premature admission to a long-term care facility. Research has shown that post-acute care is a cost-effective service model, with both the hospital-at-home and community hospital post-acute care models being highly effective. This paper describes the post-acute care models of the United States and the United Kingdom and uses the example of Taiwan’s highly effective post-acute care system to explain the benefits and importance of post-acute care. In the face of rapid demographic aging and smaller household size, a post-acute care system can lower medical costs and improve the health of older adults after hospitalization.