Adults with autism spectrum disorder (ASD) are at increased risk of suicide compared to the general population. Research has yet to identify the mechanisms underlying this increased risk. This study examined perceived social support as a potential protective factor for depressive symptoms and suicidal ideation in 76 adults with ASD. Twenty-five percent of participants were in the clinical range for depression, and 20% reported recent suicidal ideation. Social support in the form of appraisal and belonging was not associated with depression or ideation; however the perceived availability of tangible (material) support indirectly acted on ideation through depression. The findings suggest that tangible support, but not appraisal or belonging, may act as an indirect protective factor against suicidality in ASD.