Osteosarcopenia is a phenotype resulting from the combination of sarcopenia and low bone mineral density. Based on the relationship between bone and muscle, this phenotype is associated with a higher risk of falls, fractures, dependence, and health care costs than its individual components. Given its characteristics, it can be considered as a new geriatric syndrome. Therefore, understanding its pathophysiology and diagnosis, as well as its non-pharmacological and pharmacological management is a task of great importance. The problem in addressing this phenotype arises from the tradition of managing sarcopenia and osteoporosis separately. There is also a lack of consensus on what to call it (sarco-osteopenia, sarco-osteoporosis, osteosarcopenia). The aim of this review is to outline the epidemiology, pathophysiology, diagnoses, adverse events, and management of osteosarcopenia.