Hip fractures are a major cause of morbidity and mortality, and malnutrition is a critical determinant of these outcomes. This systematic review and meta-analysis aims to determine whether oral nutritional supplementation (ONS) improves postoperative outcomes in older patients with hip fracture. An electronic systematic literature search was conducted in August 2022 using four databases. Randomized trials documenting ONS in older patients with hip fracture (aged 50+) were included. Two reviewers evaluated study eligibility, data extraction and assessed study quality. There were 812 studies identified of which 18 studies involving 1,512 patients met the inclusion criteria. The overall meta-analysis demonstrates that ONS was associated with a significant risk reduction in infective complications (odds ratio (OR) 0.54, 95%CI 0.38, 0.76), pressure ulcers (OR 0.54, 95%CI 0.33, 0.88), total complications rate (OR 0.57, 95%CI 0.42, 0.79). Length of hospital stay (LOS) was also significantly reduced (weighted mean difference (WMD) −2.01, 95%CI −3.52, −0.5), particularly in the rehabilitation LOS (WMD −4.17, 95%CI −7.08, −1.26). There was a tendency towards lower risk in mortality (OR 0.93, 95%CI 0.62, 1.4) and readmission (OR 0.52, 95%CI 0.16, 1.73), though statistical significance was not achieved. The overall compliance to ONS ranged from 64.1% to 100%, but no factors influencing compliance were identified. This systematic review was the first to quantitatively demonstrate that ONS reduces half the risk of infective complications, pressure ulcers, total complication rate and reduces LOS. ONS should be a regular and integrated part of medical practice, especially given that the compliance to ONS is acceptable.