BACKGROUND: Emotional support (ES) is the most frequently reported support need among older adults with cancer. Yet, the association of ES with cancer outcomes is largely unknown. This study examined the association of ES with health-related quality of life (HRQoL), mental health, and survival among older adults with gastrointestinal (GI) malignancies. METHODS: We included newly diagnosed older adults (≥60 years) with GI cancer undergoing self-reported geriatric assessment at their first clinic visit. ES was measured using an adaptation of the Medical Outcomes Study (dichotomized adequate ES vs. inadequate ES). Outcomes included physical and mental HRQoL, anxiety, depression, and survival. Multivariable linear regression evaluated the association between ES and HRQoL scores. Multivariable logistic regression evaluated the association of ES with anxiety and depression. All models were adjusted for age at geriatric assessments, race, sex, and cancer type/stage. RESULTS: 795 participants were included. Median patient age was 68 years (IQR: 64-74), 58% were male, and most cancers were either colorectal (37.9%) or pancreatic (30.8%). Most (77.6%) had adequate ES. Patients with inadequate ES were more likely to be Black (31.5 vs. 20.8%, p = 0.005), disabled (24.1 vs. 10.4%, p < 0.001), widowed/divorced (54.2 vs. 24.8%, p < 0.001) and had lower physical and mental HRQoL t-scores (Physical β: -3.35, 95% CI: -5.25, -1.46; Mental β: -2.46, 95% CI: -4.11, -0.81) and higher odds of depression (aOR: 2.22, CI: 1.34-3.69). This study found no difference between those with adequate ES versus inadequate ES in the proportion of deaths within 1 year of diagnosis (24.3% vs. 24.2%, p = 0.966), or within 2 years of diagnosis (32.4% vs. 33.2%, p = 0.126). CONCLUSIONS: Older adults with inadequate ES have worse physical and mental HRQoL and higher odds of depression compared to those with adequate ES.