Purpose <p>The ongoing demographic transition toward an aging population is accompanied by a rising number of geriatric patients with cancer. Anemia is a common finding in older patients with malignancy. This study aimed to evaluate the prevalence of anemia and its association with functional status and depression among treatment-naïve geriatric patients with solid organ cancer (SOC).</p> Methods <p>In this observational study, geriatric patients with SOC underwent screening for anemia and a comprehensive geriatric assessment (CGA). Those with anemia were further evaluated with iron studies, stool for occult blood, upper and lower gastrointestinal endoscopies, serum B12 and folate levels, Coombs test, serum lactate dehydrogenase levels, and a bone marrow examination, as appropriate. Descriptive statistics (mean, median, and standard deviation), Pearson’s chi-square test, Fisher’s exact test, Kruskal–Wallis test, and Wilcoxon-Mann–Whitney <i>U</i> test were used to analyze the data.</p> Results <p>One hundred and seventy-six patients were included. The median age was 67 (range 60–94) years, with a male preponderance of 76.7% (<i>n</i> = 135) and a stage IV, 81.8% (<i>N</i> = 144) disease. Anemia was detected in 51.7% (<i>n</i> = 91) of patients, with 51.6% (<i>n</i> = 47) having grade 2 severity. Iron deficiency anemia (IDA), functional IDA, possible functional IDA, and no iron deficiency (NID) were found in 23.1% (<i>n</i> = 21), 44% (<i>n</i> = 40), 12.1% (<i>n</i> = 11), and 16.5% (<i>n</i> = 15) of the patients, respectively. We found a significant association of anemia with body-mass index (<i>P</i> = 0.017), performance status (<i>P</i> &lt; 0.005), activities of daily living (<i>P</i> &lt; 0.010), instrumental activities of daily living in males (<i>P</i> &lt; 0.034), balance and mobility (<i>P</i> = 0.016), and depression (<i>P</i> &lt; 0.001).</p> Conclusion <p>More than half of the geriatric patients with SOC were anemic at presentation, with functional IDA being the most common subtype, followed by IDA. Anemia was significantly associated with poorer functional status, impaired mobility and balance, and higher rates of depression, underscoring its substantial impact on both the physical and psychological well-being of older patients with cancer. These findings highlight the importance of comprehensive geriatric assessment and detailed characterization of anemia subtypes, including IDA, functional IDA, possible functional IDA, and NID, as management strategies may vary according to iron status.</p>