To analyse the effect of exercise-based rehabilitation programs for improving lower limb muscle strength in individuals with hip or knee osteoarthritis (OA). A systematic search utilizing seven databases identified randomized controlled trials (RCTs) evaluating lower limb strength outcomes of exercise-based interventions for participants with hip or knee OA. All studies were screened for eligibility and methodological quality. Quality of evidence was assessed using Grading of Recommendation, Assessment, Development and Evaluation (GRADE) approach. Data were pooled and meta-analyses performed where appropriate. Forty RCTs were included and the majority (77%) involved resistance based exercise programs. For knee OA populations, there was high quality evidence for improved knee extension (standardized mean difference (SMD) = 0.47, 95% confidence intervals (CI) 0.29, 0.66) and flexion strength (SMD = 0.74, 95% CI 0.56, 0.92) with low-intensity resistance program when compared to a control at short term (ST) follow-up. There was moderate quality evidence for a large effect favouring high-intensity resistance programs (SMD = 0.76, 95% CI 0.47, 1.06) when compared to a control. This effect was sustained at intermediate term (IT) follow-up (SMD = 0.80, 95% CI 0.44, 1.17). Few studies reported on outcomes at long term (LT) follow-up. Only one study reported on a population with hip OA. When compared to a control group, high-intensity resistance exercise demonstrated moderate quality of evidence for large and sustained improvements for knee muscle strength in knee OA patients. Further work is needed to compare different modes of exercise at a LT follow-up for knee OA patients and to address the dearth of literature evaluating exercise interventions in people with hip OA.