Sarcopenic obesity is the coexistance of sarcopenia and obesity. Modern sarcopenia definition includes low muscle mass, weak muscle strength (handgrip strength) and poor physical function (slow walking), although the clinical definition of each varies worldwide. The cut-points for low muscle mass for men and women using appendicular lean mass divided by height (kg/m2) are ≤7.0 and ≤5.4 in Asians, and ≤7.23 and ≤5.67 in Caucasians, respectively. The cut-points for weak handgrip strength (kg) for men and women areAsians, andCaucasians, respectively. The cut-point for slow walking is ≤0.8 m/s in men and women. Current data suggest the potential benefits of physical activity and fitness on sarcopenic obesity in older adults. Lay abstract: Sarcopenic obesity (SO) is the combination of low muscle mass (sarcopenia) and obesity. The average prevalence of SO is about 5–10%. Older adults with SO have higher risks of mobility disability, cardiometabolic diseases and mortality. The medical problems related to SO are much greater than that in sarcopenia or obesity alone. Current studies suggest the potential benefits of physical activity, fitness and resistance exercise on the prevention and treatment of SO in older adults. This review highlights the importance of the development of effective public health strategies to prevent, delay and treat SO in older people.