Background: The COVID-19 pandemic poses risks to the quality of life (QoL) of relatives of individuals with intellectual disabilities. This paper investigates relatives' QoL and associated risk and buffering factors before and during the pandemic. Method: Surveys were administered to three samples of relatives in the Netherlands in 2019 (N = 105) and during the first waves of COVID-19 in June (N = 207) and October 2020 (N = 332). Associations between QoL and care burden, care competence, social support, and resilience, and changes over time were analysed using (logistic) regressions. Results: No significant changes in overall QoL nor its domains were found. Care burden was negatively associated with QoL and increased during the pandemic. Care competence was lower than in 2019. Competence, social support, and resilience were positively associated with QoL. Conclusions: Although relatives' QoL remained stable, the pandemic poses non-negligible risks to their wellbeing. It is, therefore, crucial to provide relatives with adequate support.