Background: To date, no studies have examined the prevalence of hoarding behaviour and domestic squalor among individuals with mild intellectual disability. To address this gap, we conducted a prevalence study within a population supported by a medium-sized care organisation in the Netherlands. Method: Data were collected on 437 individuals with mild intellectual disability receiving care in residential facilities or through outpatient services. Assessments were conducted using the Hoarding Rating Scale-Interview, the Environmental Cleanliness and Clutter Scale, and the Clutter Image Rating Scale. Results: Hoarding behaviour and/or domestic squalor were observed in 16.8% of the residents. Support staff identified 8.3% of dwellings as posing significant safety risks or health hazards. Additionally, 6.7% of residents had been threatened with eviction due to hoarding or squalor. Conclusions: Hoarding behaviour and domestic squalor appear to be more prevalent among individuals with mild intellectual disability in care settings than among the overall population.