Background: Total Knee Replacement (TKR) surgery is typically performed to alleviate symptoms of severe, advanced osteoarthritis of the knee. TKR surgery has been shown to be an effective treatment to relieve pain and increase functional ability in the affected knee. However, after surgery a substantial subset of patients continue to experience pain, do not demonstrate anticipated functional improvements, and/or are dissatisfied with the outcomes. Recent literature has suggested that psychosocial factors can influence recovery following TKR however, the most influential psychosocial factor has not been identified. A greater understanding of the factors that affect TKR surgery outcomes is needed. Aims: The aims of the current study were: (1) to conduct a systematic review the literature investigating the influence of preoperative psychosocial factors in TKR outcomes; and to (2) investigate the relationship between preoperative psychosocial variables and rehabilitation engagement and TKR outcomes in a sample of Irish patients. Methods: The study adopted a prospective cohort design. Patients were recruited during their pre-surgical assessment. Variables were assessed using self-report measures at two time points: two-six weeks before surgery (Time 1) and six-months after surgery (Time 2). Engagement in rehabilitation was assessed during inpatient physiotherapy. Results: Eighty-two participants were included at Time 1 and 46 were included at Time 2. Mental health, measured at Time 1, contributed significantly to the variance of postoperative patient satisfaction. Unfulfilled expectations, measured at Time 2, contributed significantly to the variance of postoperative pain intensity. These findings suggest that people with lower preoperative mental health and unfulfilled expectations are at risk of poor outcomes after TKR. Thirty-two articles were included in the systematic review. Thirty articles reported significant associations between that preoperative psychosocial factors and TKR outcomes (e.g. pain intensity, functional ability and patient satisfaction). Clinical implications: Preoperative psychological screening may help to identify those in need of preoperative counselling or education regarding the formation of realistic postoperative expectations. This could ultimately improve outcomes and rates of dissatisfied patients.