Background: Women with intellectual disabilities confront distinct challenges as they age, compounded by cognitive and adaptive constraints. These challenges encompass heightened health risks, barriers to social support and susceptibility to violence, underscoring the critical role of self-determination in enhancing their quality of life. Method: This quantitative study utilised a scale based on the Functional Model of Self-Determination to assess self-determination levels in 218 Chilean women aged 45 to 80 with intellectual disabilities. The research also explored potential personal and environmental factors influencing these levels. Findings: Employed participants and those in supportive family environments demonstrated higher self-determination levels. Moreover, women without mental health issues exhibited advanced skills in self-regulation, empowerment and self-realisation. Significant disparities were noted based on varying levels of intellectual disability, types of support received and socioeconomic status, highlighting the necessity for tailored and diversified support systems. Conclusion: Developing personalised support programs that address individual and contextual differences is crucial. Despite limitations, this study emphasises the urgency for inclusive public policies aimed at eliminating socioeconomic and cultural barriers, thereby fostering environments conducive to community engagement and autonomous decision-making.