<b><i>Introduction:</i></b> Patients can have features of both chronic obstructive pulmonary disease (COPD) and asthma. However, there is still no consensus how to precisely define this patient population. In addition, there are little data on the effectiveness of biologics in these patients. <b><i>Method:</i></b> Presence of COPD was defined by a smoking history of ≥10 pack years (PY), a postbronchodilator FEV<sub>1</sub>/FVC ratio < lower limit of normal (LLN) and FEV<sub>1</sub> < 80% predicted, a carbon monoxide diffusion capacity (DLCO) < LLN, and dyspnoea on exertion as a leading symptom. Presence of asthma was defined by high type 2 biomarkers (blood eosinophils ≥300 cells/μL and/or FeNO ≥50 ppb), typical clinical features of asthma (including nocturnal respiratory symptoms), and a documented history of a clinical benefit from inhaled and/or oral glucocorticoid treatment. We analysed data from 20 patients fulfilling the criteria for both COPD and asthma who were newly treated with a biologic due to recurrent exacerbations despite high-dose inhaled triple therapy. <b><i>Results:</i></b> Median values before treatment with a biologic were as follows: 40 PY, FEV<sub>1</sub> 42% predicted, DLCO 45% predicted, 475 eosinophils/μL blood, FeNO 48 ppb. Median duration of biologic treatment (mepolizumab, benralizumab, dupilumab, omalizumab, or tezepelumab) was 12 months. There were significant improvements in exacerbations (most prominent effect), asthma control, and lung function during biologic treatment. <b><i>Conclusions:</i></b> Various types of biologics approved for severe asthma treatment can be effective in patients with both COPD and asthma. We propose an easy-to-use definition of these patients for routine clinical practice.