Introduction Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide. Malnutrition is a common and under-recognized comorbidity in COPD, impacting muscle function, immune response, and disease progression. Methods A cross-sectional observational study was conducted on 150 COPD patients at a tertiary care hospital in Chennai. Nutritional status was assessed using body mass index (BMI), mid-arm circumference (MAC), and Mini Nutritional Assessment (MNA) scores. COPD severity was graded according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2025 criteria. Results A significant positive correlation was observed between forced expiratory volume in one second (FEV)% predicted and nutritional markers (BMI: r = 0.41, MNA: r = 0.45, MAC: r = 0.38, all p < 0.001). As COPD severity increased, nutritional status declined significantly. Comorbidities, including hypertension and depression, were more common in advanced COPD. Conclusion Nutritional status strongly correlates with COPD severity. Early nutritional assessment and targeted interventions are essential in COPD management to improve outcomes.