Background: Adults with intellectual disabilities are an at-risk group of developing dementia. In the absence of a cure for dementia, emphasis on treatment is the promotion of Quality of life (QoL). The aim of this review is to identify and describe QoL tools for people with intellectual disabilities and dementia. Method: A systematic review was carried out using 10 databases and papers from up to March year 2021. Results: Two instruments were identified and examined. The QoL in late-stage dementia, which showed evidence of good levels of internal consistency, intra-rater reliability, test-retest reliability, and convergent validity. The Dementia Quality of Life -- proxy was also used; however, its psychometric properties have yet to be studied within the intellectual disabilities population. Conclusion: It is recommended instruments should be developed and psychometrically tested specifically for adults with intellectual disabilities and dementia to help inform policy makers, measure outcomes of interventions and personal outcomes.