Sedentary behavior is one of the major risk factors for cardiovascular mortality; hence there is a need to promote physical activity (PA) among adults aged 60–86 years. The aim of this narrative review was to evaluate the role of PA in the prevention and treatment of chronic diseases among older adults. Relevant studies (original articles, systematic reviews, and meta-analyses) that reported on the effects of PA in older adults from 1998 to 2019 were selected. The following electronic databases were searched: PubMed, ScienceDirect, PsycINFO, Embase, Medline, Sports Discus, Web of Science, and Cochrane database. Physical exercise at different intensities was shown to be effective in the prevention and treatment of overweight, functional decline, and mood disorders in older adults. Moderate-to-high intensity endurance exercise can be effective in the prevention of diabetes type 2, hypertension, and cancer in older adults. Resistance training at different intensities was shown to be effective in the prevention and treatment of obesity in the elderly. Mobility and balance training were effective in preventing falls in older individuals. Combined exercise training regimen comprising moderate-to-vigorous intensity aerobic and resistance exercise is beneficial in the prevention of disability, osteoporosis, hypertension, and falls among older adults. Moreover, combined exercise training improves immune function and antioxidant capacity in older adults. Based on the studies reviewed, PA was found to be an effective tool for the prevention and treatment of chronic diseases among older adults.