Obesity is associated with a profound impairment in the ability to perform the basic physical activities required for everyday function. This impacts on quality of life and contributes to disability. Bariatric surgery leads to weight loss and metabolic improvements in severe obesity; however, less is known about its effect on physical functioning. This narrative review summarizes current evidence on the effect of bariatric surgery on this outcome with a consideration of the mechanisms involved. Nine longitudinal observational studies reporting objective measures of physical functioning were identified. Inclusion criteria, follow-up time and outcomes reported varied considerably between studies and sample sizes were small. They all showed a significant improvement in performance following surgery despite variations in baseline patient characteristics. Additionally, six studies were found in which subjects were subjected to exercise testing protocols. Performance of the test protocol improved in all. Where reported, peak oxygen uptake related to body weight improved; however, absolute values were either unchanged or decreased. In conclusion, observational evidence suggests that patients’ physical functioning improves following bariatric surgery. More evidence is required regarding mechanisms involved; however, it may be due to improved efficiency in performing activities as opposed to absolute improvements in cardiorespiratory or muscle function.