We sought to determine the comparative benefit and harm of rehabilitation interventions for patients who have undergone elective, unilateral total knee arthroplasty for the treatment of primary osteoarthritis. We searched PubMed, Embase, The Cochrane Register of Clinical Trials, CINAHL, PsycINFO, Scopus, and ClinicalTrials.gov from January 1, 2005, through May 3, 2021. We included randomized controlled trials and adequately adjusted nonrandomized comparative studies of rehabilitation programs reporting performance-based, patient-reported, or healthcare utilization outcomes. Three researchers extracted study data and assessed risk of bias, verified by an independent researcher. The team assessed strength of evidence. Evidence from 53 studies randomized controlled trials suggests that various rehabilitation programs after total knee arthroplasty may lead to comparable improvements in pain, range of motion, and activities of daily living. Rehabilitation in the acute phase may lead to increased strength but result in similar strength when delivered in the postacute phase. No studies reported evidence of risk of harms due to rehabilitation delivered in the acute period after total knee arthroplasty; risk of harms among various postacute rehabilitation programs seems comparable. All findings were of low strength of evidence. Evaluation of rehabilitation after total knee arthroplasty needs a systematic overhaul to sufficiently guide future practice or research including the use of standardized intervention components and core outcomes.