Background Caregivers of cancer patients are at increased risk of depression and other health challenges. There is limited understanding of the role of the caregiver’s own family members in promoting or discouraging mental wellbeing. Family functioning conceptualizes how family members interact to promote a positive family environment and has the potential to impact caregiver mental health. The purpose of this study is to assess the association between family interactions and depressive symptoms among family caregivers of cancer patients. Methods Secondary analysis of baseline data from an NIH-funded randomized control trial of family caregivers of cancer patients recruited from academic palliative care clinics at three sites (2 Midwest, 1 East). We tested for an association between caregiver responses to the Family Quality of Life in Dementia-Family Interactions Subscale and Patient-Reported Outcomes Measurement Information System Depression Short Form 8A using a block-wise approach to linear modeling. Results A total of 246 caregivers were included in analysis; caregivers were mostly White (82%), not Hispanic or Latina/o (96%), and female (65%), with an average age of 55 years. Overall, participants had high family interactions (mean 57.7, sd 11.7) and an average depressive symptom burden (t-score 52.4, SD 8.57). Family interactions was significantly negatively associated with depressive symptoms (b = −.163, se = .057) when accounting for relevant covariates. Conclusion Family caregivers with more positive family interactions are likely to have fewer depressive symptoms, suggesting family functioning may play a key role in bolstering family caregiver mental health and wellbeing.