REM-sleep behavior disorder (RBD) may affect health-related quality of life (HRQoL) of people with Parkinson's disease (PwP) and partners. We aimed to determine how RBD affects HRQoL using a mixed-methods approach. Quantitatively, we analyzed data from the PRIME-NL Parkinson Evaluation study, including 829 PwP and 452 partners, using multivariable regression models to examine the association between screen-positive RBD and HRQoL. Qualitatively, we conducted interviews with 14 dyads of PwP with self-reported RBD and their partners. RBD was negatively associated with HRQoL in both groups, primarily due to short-term effects on daily life, co-existing symptoms like impaired cognition and autonomic issues, and sleep disturbances. Impact of RBD was already felt before or during the diagnostic process, with the main challenges being sleep-related complaints, anxiety and impact on relationships. PwP and partners employed both medical and non-medical coping strategies. These findings will help to optimize care for PwP with RBD and their partners.