Purpose: The impact of pain on functional status and mental health among older adults with cancer is a relevant, yet understudied. We sought to identify the prevalence of pain at diagnosis in older adults with gastrointestinal (GI) malignancies and evaluate the association of pain with functional status limitations, cognition, and mental health. Methods: This prospective cross-sectional study included older adults (age ≥ 60) with GI cancers enrolled in the CARE Registry. Pain measured in numeric rating scale from 0 to 10. We utilized the literature based cutoff for moderate-severe as ≥ 4. Logistic regression used to assess differences in functional status, falls, cognitive complaints, and depression/anxiety associated with moderate/severe pain, adjusted for sex, race, education, ethnicity, marital status, cancer type/stage, and treatment phase. Results: Our cohort included 714 older adults with an average mean age of 70 years and 59% male. Common diagnoses included colorectal (27.9%) and pancreatic (18%). A total of 43.3% reported moderate/severe pain. After multivariate adjusting for covariates, participants with self-reported moderate/severe pain were more likely to report limitations in instrumental activities of daily living (adjusted odds ratio [aOR] 4.3 95% confidence interval [CI] 3.1–6.1, p <.001), limitation in activities of daily living (aOR 3.2 95% CI 2.0–5.1, p <.001), cognitive complaints (aOR 2.9 95% CI 1.4–6.0, p <.004), anxiety (aOR 2.2 95% CI 1.4–3.4, p < 0.01), and depression (aOR 3.7 95% CI 2.2–6.5, p <.001). Conclusions: Pain is common among older adults with GI cancers and is associated with functional status limitations, cognitive complaints, and depression/anxiety. Strategies to reduce pain and minimize its potential impact on function and mental health warrant future research.