Background: Meningiomas are common brain neoplasms that can significantly influence health-related quality of life (HRQOL), yet the factors influencing HRQOL in adult patients remain unclear. We aimed to bridge this knowledge gap by determining these key factors. Methods: We conducted a systematic review, searching EMBASE, MEDLINE, CINAHL, Scopus, and PsycINFO up to March 2023. We included original, peer-reviewed studies focusing on adult patients (>18 years) with current or past meningioma at any stage of treatment that measured HRQOL or its proxies in relation to tumour-, treatment-, and patient-related factors. Two independent reviewers screened abstracts and full texts, selecting studies with acceptable risk of bias for data extraction and narrative synthesis. Results: Of N=2942 identified studies, N=30 were included. Key factors found to influence HRQOL in adult meningioma patients include surgery, radiotherapy, neurological function, functional status, comorbidities, sleep quality, psychological impairment, age, and employment. Factors related to tumour characteristics yielded inconsistent findings. Heterogeneity and inconsistencies in HRQOL measurement across studies hindered definitive conclusions about the impact of factors on HRQOL. Conclusions: Our review emphasizes the need for standardized, disease-specific HRQOL assessments in meningioma patients. More consistent, large-scale, prospective research is essential to comprehensively understand and improve HRQOL, and thereby ensure tailored care for this population.