Background <p>Biological sex may influence postoperative outcomes after total hip arthroplasty (THA) through differences in bone biology, muscle function, immune response, and systemic recovery. However, clinical evidence on sex-specific outcome patterns remains inconsistent and fragmented. The objective of this review was to systematically evaluate the influence of biological sex on postoperative outcomes, complication risk, and recovery trajectories following primary THA.</p> Methods <p>A systematic review was conducted according to preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines and registered in the International Prospective Register of Systematic Reviews (PROSPERO). PubMed, Scopus, and Web of Science were searched for studies published between December 2015 and December 2025, comparing postoperative outcomes between female and male patients undergoing primary THA. Study selection, data extraction, and risk-of-bias assessment (risk of bias in nonrandomized studies—of interventions (ROBINS-I)) were performed independently by multiple reviewers. Owing to substantial heterogeneity, a qualitative synthesis was conducted.</p> Results <p>A total of 26 studies encompassing over 2.3 million patients were included, predominantly retrospective cohort and registry-based analyses. Sex-specific differences were observed across multiple outcome domains, including revision risk, periprosthetic femoral fracture (PFF), complications, discharge patterns, and patient-reported outcomes. Women demonstrated a modestly higher risk of revision and PFF in specific age groups, particularly younger patients and elderly individuals receiving uncemented fixation. By contrast, men exhibited higher rates of early medical complications, including cardiac events, acute kidney injury, and mortality. Implant fixation strategy and design interacted with sex and age to influence revision risk. Patient-reported outcomes revealed sex-specific recovery patterns, with women experiencing greater improvements in mental quality of life and pain relief, while men showed faster early physical recovery.</p> Conclusions <p>Sex significantly modulates postoperative outcomes following THA through complex interactions with age, implant choice, fixation strategy, and biological factors. Consistent sex-specific patterns were observed across complication profiles, revision risk, and recovery trajectories, supporting the clinical relevance of sex-aware risk stratification and personalized surgical planning. This review provides a comprehensive synthesis across multiple outcome domains and highlights the context-dependent nature of sex-related effects, offering a clinically oriented framework for interpreting these differences. However, the predominance of retrospective and registry-based studies, along with substantial heterogeneity in outcome definitions and adjustment strategies, limit the ability to draw definitive causal inferences. Well-designed prospective studies and randomized controlled trials are warranted to validate these findings and to clarify the mechanisms underlying sex-related differences in THA outcomes.</p> Level of evidence <p>Level III.</p> Registration <p><a href="https://www.crd.york.ac.uk/PROSPERO/view/CRD420261290382">https://www.crd.york.ac.uk/PROSPERO/view/CRD420261290382</a></p>