Frailty is a distinct phenotype that is highly prevalent in chronic kidney disease (CKD) and appears to be more prevalent with decreasing glomerular filtration rate. Exercise training or intervention to increase physical activity may ameliorate poor physical functioning and frailty, and even may improve survival in patients with CKD. Although exercise interventions improve outcomes across the spectrum of CKD, including patients treated with dialysis, patients treated with dialysis face barriers to exercise that patients with predialysis CKD do not. Rehabilitation at earlier stages of CKD (or prehabilitation before dialysis) might be more beneficial than not addressing the decreasing physical functioning and low physical activity until patients are receiving dialysis. This review summarizes available literature on frailty in the CKD and end-stage renal disease population, including exercise interventions and the limited evidence for prehabilitation as a strategy.