Osteosarcopenia is a geriatric syndrome characterised by the co-existence of osteoporosis and sarcopenia, two chronic musculoskeletal conditions associated with ageing. This syndrome may lead to falls and fractures, increased morbidity, mortality and disability, and reduced quality of life. The etiopathogenesis of osteosarcopenia is multifactorial; mechanical, biochemical, genetic and lifestyle factors all play important roles. Its prevalence has been reported between 5% and 37%. The varied prevalence is likely due to the heterogeneous populations or non-unified diagnostic criteria for this syndrome. Osteosarcopenia can be diagnosed by detailed clinical assessment (e.g. screening and risk calculation tools, grip strength, physical performance tests), laboratory tests and imaging methods. Dual-energy X-ray absorptiometry is the most common method used in measuring bone mineral density for the diagnosis of osteoporosis. The imaging techniques used to detect loss of skeletal muscle mass in sarcopenia are dual-energy X-ray absorptiometry, computed tomography, ultrasonography and magnetic resonance imaging. Treatment options for osteosarcopenia include exercise, nutritional supplements (protein, vitamin D, calcium and creatine), life style modifications and pharmacological therapy. With increasing understanding of the underlying mechanisms of osteosarcopenia, the development of therapeutic agents targeting both muscle and bone has become a new area of investigation. This review summarises the epidemiology, pathophysiology, diagnosis and treatment of osteosarcopenia in the light of the relevant literature.