Background <p>This systematic review and meta-analysis aimed to compare postoperative gait and functional outcomes between the Hardinge approach (HA) and the posterolateral approach (PLA) for total hip arthroplasty (THA).</p> Methods <p>A comprehensive literature search was conducted in PubMed and Embase for studies directly comparing HA and PLA. Eligible studies were selected based on predefined inclusion and exclusion criteria. Two reviewers independently performed study screening, quality assessment, and data extraction.</p> Results <p>Twenty-six studies, including 245,620 patients (HA: <i>n</i> = 88,193; PLA: <i>n</i> = 157,427), were included. Compared to the HA group, the PLA group was associated with better gait velocity and abductor muscle strength, while the HA group exhibited a lower hip dislocation rate but higher risks of heterotopic ossification and infection. No significant intergroup differences were found in the Harris Hip Score, stride length, ground reaction force, periprosthetic fracture, or radiographic outcomes.</p> Conclusions <p>This meta-analysis suggests that PLA offers advantages in gait velocity and abductor power recovery, while HA is associated with a lower dislocation rate. This potential benefit of HA must be balanced against its observed higher risks of heterotopic ossification and surgical site infection. These findings, however, are derived from observational studies with inherent confounding factors, such as variations in implant design and surgical technique. Therefore, the reported outcome differences may not be attributable solely to the surgical approach.</p> Trial registration <p>Registration ID, CRD42025634164.</p> Clinical trial number <p>Not applicable.</p>