Background: Malnutrition is a common cause of morbidity and mortality in patients with cancer. Malnutrition is seen in 40 to 80% of patients with cancer. Recent literature has shown loss of lean body mass in cancer population can be an independent factor for poorer outcomes. Anorexia, the loss of appetite has been either secondary to the disease itself or as a side effect of treatment. The mechanism of anorexia development is due to physiologic alteration in metabolism during carcinogenesis. Hence, it becomes important to screen for malnutrition in all patients with diagnosis of cancer. Methods: This single-center cohort study, conducted between January 15, 2024, and February 9, 2024, involved 106 patients receiving outpatient oncology care. Patients aged 18 to 90 years who consented to participate were administered the Mini Nutritional Assessment (MNA) questionnaire at the oncology registration desk. Exclusion criteria included patients with a dietician and those with pure nonmalignant hematological diagnoses. Data analysis comprised identifying patients at risk of malnutrition (8-11 points) or malnourished (0-7 points) using the MNA scale, followed by retrospective chart review. Primary outcomes focused on identifying prevalent cancer types among malnourished or at-risk patients, while secondary outcomes included comparing malnutrition proportions among different treatment groups and assessing gastrointestinal tract metastases and common causes of malnutrition. Results: The data encompassed 106 patients, among whom 29 (27.3%) were identified as at risk of malnutrition, while 9 (8.4%) were malnourished. Notably, a majority of at-risk or malnourished patients (60.5%) were classified as overweight or obese. The most prevalent cancers among these patients were breast cancer (26.3%), genitourinary cancer (23.6%), and gastrointestinal cancer (18.4%). Chemotherapy use was noted in 16 (42.1%) patients, immune checkpoint inhibitor treatment in 12 (31.5%), and a combination of both in 7 (18.4%). Gastrointestinal metastasis was observed in 5 (13.1%) patients. Among those at risk of malnutrition, the primary contributing factors identified were tumor impact and location (63.1%), diarrhea (18.4%), and fatigue (18.4%). Conclusions: The study underscores the significant prevalence of malnutrition risk among cancer patients, emphasizing the importance of systematic screening during outpatient oncology follow-ups.