Background: Sexual dysfunction (SD) and sleep disturbances are frequent but underrecognized non-motor symptoms in Parkinson’s disease (PD) and significantly affect quality of life. However, the relationships among sexual dysfunction, sleep quality, and excessive daytime sleepiness (EDS) and the possible sex-related differences remain insufficiently investigated. Methods: In this cross-sectional case–control study, we evaluated these non-motor symptoms in 147 Turkish patients with PD and 160 age- and sex-matched healthy controls, and we assessed their associations and impact on quality of life, with particular attention to sex-specific patterns. Sexual function was assessed using the Arizona Sexual Experiences Scale (ASEX), sleep quality using the Pittsburgh Sleep Quality Index (PSQI), daytime sleepiness using the Epworth Sleepiness Scale (ESS), quality of life using the 39-item Parkinson’s Disease Questionnaire (PDQ-39), and disease severity using the Unified Parkinson’s Disease Rating Scale (UPDRS) and Hoehn and Yahr (H&Y) staging scale. Group comparisons, correlation analyses, and sex-stratified subgroup analyses were performed. Results: Patients with PD had significantly higher ASEX, PSQI, and ESS scores compared with controls (p < 0.01), and women with PD had significantly higher total ASEX scores than men, indicating greater sexual dysfunction. Sexual dysfunction was significantly associated with poor sleep quality and excessive daytime sleepiness but showed no significant association with the motor severity measures (UPDRS, H&Y stage). Sleep quality, as measured via PSQI scores, was worse in patients with PD, and poor sleep quality and excessive daytime sleepiness were both associated with significantly worse quality of life. Conclusions: According to our findings, sexual dysfunction and sleep disturbances are interrelated non-motor symptoms that significantly impair quality of life, largely independently of motor severity, and these associations were particularly pronounced among women. A combined evaluation of sleep and sexual function may therefore improve the recognition and management of the non-motor burden in PD.