Background: Can disability support services (DS) facilitate access to mental health services (MHS) for people with intellectual disability? This study utilized 10 years of data from 6,260 persons in NSW who had received DS and specific MHS to quantify the relationship between DS utilization and MHS utilization in adults with intellectual disability and co-existing mental illness. Results: Receipt of DS was associated with greater odds of accessing community mental health (CMH) services (36%, 95% CI 29%-43%) but not psychiatric admissions. Age, sex and social disadvantage did not affect the odds of psychiatric admission or CMH use. Individuals living in a remote area had greater odds of CMH use and lesser odds of psychiatric admission. Conclusions: Receipt of DS was associated with greater CMH but not psychiatric hospital utilization in people with intellectual disability and co-existing mental illness.