This study aimed to identify perspectives of relatives and healthcare professionals regarding self-determination support for people with severe or profound intellectual and multiple disabilities, highlighting agreements and differences in their viewpoints. Following a concept mapping study, online focus group meetings yielded statements on self-determination support from relatives (residential facilities: n = 6, family homes: n = 7) and healthcare professionals (residential facilities: n = 9, family home: n = 5). Participants clustered and rated statements, resulting in four concept maps interpreted by experts (N = 6). The 285 statements were categorised into 5-7 clusters per map, revealing key strategies for self-determination support: communication and choice making (facilitated by aids), sensitivity, familiarity, and collaboration among involved parties. Each group placed different emphasis on these strategies, highlighting importance of continuous support in their implementation. Future research should prioritise practical implementations of these strategies to enhance self-determination.