Abstract Background A measure to provide insight regarding health‐related quality of life of adults with severe motor and intellectual disabilities was lacking. For this reason, the CPADULT was developed. This measure includes domains relating to an individual's physical, mental, and social functioning. The purpose of this study was to assess the psychometric characteristics of the CPADULT. Method Caregivers ( n = 47; 77% female, 23% male) of individuals with severe disabilities who are non‐ambulatory completed the questionnaire. Internal consistency, test–retest reliability and construct validity were analysed. Results Internal consistency was adequate with Cronbach's alpha values from 0.75 to 0.95. Test–retest reliability was good, as intraclass correlation coefficient of the total score was 0.84 (domains: 0.61–0.89). Construct validity was confirmed with significant differences between subgroups of motor or intellectual abilities. Conclusion The CPADULT has sufficient reliability and validity as a proxy measure of health‐related quality of life for adults with severe disabilities who are non‐ambulatory.