This study investigates the prevalence and association of sarcopenia and sarcopenic obesity (SO) with all-cause mortality in a large, population-based cohort of older adults. The Rotterdam Study, which included 5888 participants, found that 11.1% had probable sarcopenia, 2.2% had confirmed sarcopenia, 5.0% had SO with one altered component of body composition, and 0.8% had SO with two altered components. Participants with confirmed sarcopenia or SO had a significantly increased risk of all-cause mortality, with the highest risk observed in those with both conditions. The study highlights the importance of early identification and intervention for sarcopenia and SO to improve outcomes in older adults.This study investigates the prevalence and association of sarcopenia and sarcopenic obesity (SO) with all-cause mortality in a large, population-based cohort of older adults. The Rotterdam Study, which included 5888 participants, found that 11.1% had probable sarcopenia, 2.2% had confirmed sarcopenia, 5.0% had SO with one altered component of body composition, and 0.8% had SO with two altered components. Participants with confirmed sarcopenia or SO had a significantly increased risk of all-cause mortality, with the highest risk observed in those with both conditions. The study highlights the importance of early identification and intervention for sarcopenia and SO to improve outcomes in older adults.