Chronic obstructive pulmonary disease (COPD) is one of the main public health problems in the world. One of the reasons for that is a vast heterogeneity of pathogenetic mechanisms and clinical manifestations, because of which one therapeutic strategy cannot be successfully applied to all patients. Instead, a personalized approach is needed. That’s why the scientific community is looking for biomarkers that could help identify subgroups of patients with common characteristics and thus increase the efficacy of current therapeutic interventions, as well as accelerate the development of new ones. There is a great number of research papers that explore the association of different biomarkers with clinical and therapeutic outcomes. One of the most significant biomarkers is the blood eosinophil count. Higher eosinophil count predicts a better response to inhaled corticosteroids and is therefore included in the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines as a criterion for initiating that treatment. Some articles indicate an association of higher blood eosinophil counts with a higher exacerbation risk, but the evidence is still insufficient. Beside eosinophils, concentrations of various molecules which could serve as biomarkers can be measured in the blood. Fibrinogen provides the greatest potential and is approved for use in research as a biomarker of increased risk of exacerbation and death. Among physiological biomarkers, spirometry parameters such as forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC) are already being used as diagnostic biomarkers, and diffusing capacity of the lungs for carbon monoxide demonstrated even greater association with some clinical outcomes. Among imaging methods in COPD, computed tomography (CT) has the biggest role. It can detect emphysema and chronic bronchitis, as well as potential comorbidities. Various molecules, products of lung inflammation, can be detected in samples of sputum, bronchoalveolar lavage, exhaled breath, and exhaled breath condensate. Associations of extracellular vesicles, genetic biomarkers and molecular signs of lung ageing with COPD outcomes have also been investigated. Clinical implementation of these biomarkers will probably rely on their combination, but further research is needed before it becomes possible.